1
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Sorokina AS, Gumerov RA, Noguchi H, Potemkin II. Computer Simulations of Responsive Nanogels at Lipid Membrane. Macromol Rapid Commun 2024:e2400406. [PMID: 39150327 DOI: 10.1002/marc.202400406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2024] [Revised: 08/05/2024] [Indexed: 08/17/2024]
Abstract
The swelling and collapse of responsive nanogels on a planar lipid bilayer are studied by means of mesoscopic computer simulations. The effects of molecular weight, cross-linking density, and adhesion strength are examined. The conditions for collapse-mediated engulfing by the bilayer are found. In particular, the results show that at low hydrophobicity level the increase in the nanogel softness decreases the engulfing rate. On the contrary, for stronger hydrophobicity level the trend changes to the opposite one. At the same time, when the cross-linking density is too low or the adhesion strength is too high the nanogel deformation at the membrane suppresses the engulfing regardless of the network swelling ratio. Finally, for comparative reasons, the behavior of the nanogels is also studied at the solid surface. These results may be useful in the design of soft particles capable of tuning of their elasticity and porosity for successful intracellular drug delivery.
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Affiliation(s)
- Anastasia S Sorokina
- Physics Department, Lomonosov Moscow State University, Moscow, 119991, Russian Federation
| | - Rustam A Gumerov
- Physics Department, Lomonosov Moscow State University, Moscow, 119991, Russian Federation
| | - Hiroshi Noguchi
- Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba, 277-8581, Japan
| | - Igor I Potemkin
- Physics Department, Lomonosov Moscow State University, Moscow, 119991, Russian Federation
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2
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Sergeev AV, Rudyak VY, Kozhunova EY, Chertovich AV, Khokhlov AR. Theoretical Study of Microgel Functional Groups' Mobility. J Phys Chem B 2023; 127:11083-11090. [PMID: 38095423 DOI: 10.1021/acs.jpcb.3c06599] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2023]
Abstract
Polymer microgels, micrometer-sized cross-linked polymer particles, are considered to be a promising type of advanced materials for a wide range of applications. To enhance the microgels' applicability, it is essential to incorporate various functional groups into a microparticle polymer network. Yet, the availability of functional groups for the interaction with surroundings depends strongly on the properties of the polymer network and has a great impact on further effective usage. In this theoretical study, we address this question and, with the help of coarse-grained molecular dynamics computer simulations, assess the segmental mobility and accessibility of functional groups bound to polymer network depending on microgel architecture and solvent quality. Additionally, we evaluate the minimum number of functional groups needed to facilitate the hopping mechanism between the functional groups (i.e., charge transfer). As an example of practical implementation of the obtained results, we estimate the optimal network topology for redox-active microgels to provide the maximum charge capacity for the dispersion electrolyte in redox-flow batteries.
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Affiliation(s)
- A V Sergeev
- Semenov Federal Research Center for Chemical Physics, Moscow 119991, Russia
- Faculty of Physics, Lomonosov Moscow State University, Moscow 119991, Russia
| | - V Yu Rudyak
- Faculty of Physics, Lomonosov Moscow State University, Moscow 119991, Russia
| | - E Yu Kozhunova
- Faculty of Physics, Lomonosov Moscow State University, Moscow 119991, Russia
| | - A V Chertovich
- Semenov Federal Research Center for Chemical Physics, Moscow 119991, Russia
- Faculty of Physics, Lomonosov Moscow State University, Moscow 119991, Russia
| | - A R Khokhlov
- Faculty of Physics, Lomonosov Moscow State University, Moscow 119991, Russia
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3
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Akgonullu DZ, Murray BS, Connell SD, Fang Y, Linter B, Sarkar A. Synthetic and biopolymeric microgels: Review of similarities and difference in behaviour in bulk phases and at interfaces. Adv Colloid Interface Sci 2023; 320:102983. [PMID: 37690329 DOI: 10.1016/j.cis.2023.102983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 08/12/2023] [Accepted: 08/14/2023] [Indexed: 09/12/2023]
Abstract
This review discusses the current knowledge of interfacial and bulk interactions of biopolymeric microgels in relation to the well-established properties of synthetic microgels for applications as viscosity modifiers and Pickering stabilisers. We present a timeline showing the key milestones in designing microgels and their bulk/ interfacial performance. Poly(N-isopropylacrylamide) (pNIPAM) microgels have remained as the protagonist in the synthetic microgel domain whilst proteins or polysaccharides have been primarily used to fabricate biopolymeric microgels. Bulk properties of microgel dispersions are dominated by the volume fraction (ϕ) of the microgel particles, but ϕ is difficult to pinpoint, as addressed by many theoretical models. By evaluating recent experimental studies over the last five years, we find an increasing focus on the analysis of microgel elasticity as a key parameter in modulating their packing at the interfaces, within the provinces of both synthetic and biopolymeric systems. Production methods and physiochemical factors shown to influence microgel swelling in the aqueous phase can have a significant impact on their bulk as well as interfacial performance. Compared to synthetic microgels, biopolymer microgels show a greater tendency for polydispersity and aggregation and do not appear to have a core-corona structure. Comprehensive studies of biopolymeric microgels are still lacking, for example, to accurately determine their inter- and intra- particle interactions, whilst a wider variety of techniques need to be applied in order to allow comparisons to real systems of practical usage.
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Affiliation(s)
- Daisy Z Akgonullu
- Food Colloids and Bioprocessing Group, School of Food Science and Nutrition, University of Leeds, UK
| | - Brent S Murray
- Food Colloids and Bioprocessing Group, School of Food Science and Nutrition, University of Leeds, UK
| | - Simon D Connell
- Molecular and Nanoscale Physics Group, School of Physics and Astronomy, University of Leeds, UK
| | - Yuan Fang
- PepsiCo, Valhalla, New York, NY, USA
| | | | - Anwesha Sarkar
- Food Colloids and Bioprocessing Group, School of Food Science and Nutrition, University of Leeds, UK.
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4
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Hagemans F, Camerin F, Hazra N, Lammertz J, Dux F, Del Monte G, Laukkanen OV, Crassous JJ, Zaccarelli E, Richtering W. Buckling and Interfacial Deformation of Fluorescent Poly( N-isopropylacrylamide) Microgel Capsules. ACS NANO 2023; 17:7257-7271. [PMID: 37053566 DOI: 10.1021/acsnano.2c10164] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Hollow microgels are fascinating model systems at the crossover between polymer vesicles, emulsions, and colloids as they deform, interpenetrate, and eventually shrink at higher volume fraction or when subjected to an external stress. Here, we introduce a system consisting of microgels with a micrometer-sized cavity enabling a straightforward characterization in situ using fluorescence microscopy techniques. Similarly to elastic capsules, these systems are found to reversibly buckle above a critical osmotic pressure, conversely to smaller hollow microgels, which were previously reported to deswell at high volume fraction. Simulations performed on monomer-resolved in silico hollow microgels confirm the buckling transition and show that the presented microgels can be described with a thin shell model theory. When brought to an interface, these microgels, that we define as microgel capsules, strongly deform and we thus propose to utilize them to locally probe interfacial properties within a theoretical framework adapted from the Johnson-Kendall-Roberts (JKR) theory. Besides their capability to sense their environment and to address fundamental questions on the elasticity and permeability of microgel systems, microgel capsules can be further envisioned as model systems mimicking anisotropic responsive biological systems such as red blood and epithelial cells thanks to the possibility offered by microgels to be synthesized with custom-designed properties.
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Affiliation(s)
- Fabian Hagemans
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, DE-52074 Aachen, Germany
| | - Fabrizio Camerin
- CNR-ISC, Sapienza University of Rome, p.le A. Moro 2, 00185 Roma, Italy
- Department of Physics, Sapienza University of Rome, p.le A. Moro 2 00185 Roma, Italy
| | - Nabanita Hazra
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, DE-52074 Aachen, Germany
| | - Janik Lammertz
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, DE-52074 Aachen, Germany
| | - Frédéric Dux
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, DE-52074 Aachen, Germany
| | - Giovanni Del Monte
- CNR-ISC, Sapienza University of Rome, p.le A. Moro 2, 00185 Roma, Italy
- Department of Physics, Sapienza University of Rome, p.le A. Moro 2 00185 Roma, Italy
| | - Olli-Ville Laukkanen
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, DE-52074 Aachen, Germany
- VTT Technical Research Centre of Finland Ltd, Koivurannantie 1, 40400 Jyväskylä, Finland
| | - Jérôme J Crassous
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, DE-52074 Aachen, Germany
| | - Emanuela Zaccarelli
- CNR-ISC, Sapienza University of Rome, p.le A. Moro 2, 00185 Roma, Italy
- Department of Physics, Sapienza University of Rome, p.le A. Moro 2 00185 Roma, Italy
| | - Walter Richtering
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, DE-52074 Aachen, Germany
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5
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Palkar V, Thakar D, Kuksenok O. Nanogel Degradation at Soft Interfaces and in Bulk: Tracking Shape Changes and Interfacial Spreading. Macromolecules 2023. [DOI: 10.1021/acs.macromol.2c02470] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Affiliation(s)
- Vaibhav Palkar
- Department of Materials Science and Engineering, Clemson University, Clemson, South Carolina 29634, United States
| | - Devanshu Thakar
- Department of Materials Science and Engineering, Clemson University, Clemson, South Carolina 29634, United States
- Department of Chemical Engineering, Indian Institute of Technology, Gandhinagar 382055, India
| | - Olga Kuksenok
- Department of Materials Science and Engineering, Clemson University, Clemson, South Carolina 29634, United States
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6
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Strauch C, Schneider S. Ionisation and swelling behaviour of weak polyampholyte core-shell networks - a Monte Carlo study. SOFT MATTER 2023; 19:938-950. [PMID: 36632835 DOI: 10.1039/d2sm01301k] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
The network charge of polyampholyte microgels can be tuned by varying the pH of the surrounding solution, and a charge reversal from a positively charged microgel at low pH to a negatively charged microgel at high pH can be achieved. In a titration experiment, it is difficult to tell apart the ionisation of the acidic and basic monomers in the network and to determine the distribution of charges in the network, whereas using Metropolis Monte Carlo simulations, both the degree of ionisation and the distribution of ionised monomers can be determined separately for both species. Building on our earlier work on alternating polyampholyte microgels, we now investigated the pH-dependent ionisation and the swelling behaviour of polyampholyte core-shell microgels under good solvent conditions. For this purpose, we performed Metropolis Monte Carlo simulations for a bead-spring model using the constant-pH method. As in our previous study on alternating microgels, the width of the U-shaped curve of the microgels volume as a function of pH depends on the relative dissociation constants of acid and base, and the microgel volume can be approximated by a linear function of the total network charge. Due to the spatial separation of acid and base in core-shell systems, the ionisation is less enhanced compared to a microgel with an alternating distribution of the two species. Nevertheless, we still see an influence of the presence of one species on the ionisation behaviour of the other species under good solvent conditions. Furthermore, the isoelectric point is shifted towards higher pH, which is caused by a higher charge density in the core compared to that in the shell. Added salt changes the Donnan equilibrium, which determines the counterion distribution within and outside of the microgel. At the same time, it contributes to the electrostatic screening of the network charges, leading to a narrowing of the U-shaped volume transition curve.
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Affiliation(s)
- Christian Strauch
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, D-52056 Aachen, Germany.
| | - Stefanie Schneider
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, D-52056 Aachen, Germany.
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7
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Thongam J, Shagolsem LS. Effect of Topology on the Statics and Dynamics of a Polymer Chain at the Fluid-Fluid Interface: A Molecular Dynamics Simulation Study. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:6330-6342. [PMID: 35561420 DOI: 10.1021/acs.langmuir.2c00210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The effect of chain topology on the statics and dynamics of a chain at the interface of two immiscible fluids is studied by means of molecular dynamic simulations. For three topologically different chains, namely, linear, ring, and trefoil-knot, of the same molecular weight, the effect of varying both polymer-fluid and fluid-fluid interaction nature on the width of the fluid interface, chain conformation, shape, and chain dynamics is investigated. For a sharp-interface binary-fluid system, the interface width is insensitive to both topology and polymer-fluid interaction nature, while a weak nonmonotonic variation is seen for a broad-interface system. Chain extension normal to the interface plane is significantly affected by the topology with a trefoil-knot chain, due to the additional constraint, which has the largest value compared to both linear and ring polymers. Instantaneous shapes are also quantified through shape parameters. Furthermore, it is observed that the qualitative behavior of the center-of-mass mean-square displacement (MSD) is independent of topology, i.e., all the chain types show the same diffusion exponent α ( ∼ 1). However, the self-diffusion constant depends on the topology and it is the largest for the trefoil-knot chain. An interesting observation pertaining to the early time behavior of monomeric MSD is that, within the subdiffusive regime, the values of α for different parameters (independent of topology) are grouped into two distinct ranges (0.52 - 0.59 and 0.62 - 0.67), which are related to the different chain conformation for the polymer-fluid interaction range below and above a threshold value equal to that of the self-interaction of the pure fluid phase.
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Affiliation(s)
- Jenis Thongam
- Department of Physics, National Institute of Technology Manipur, Imphal 795004, India
| | - Lenin S Shagolsem
- Department of Physics, National Institute of Technology Manipur, Imphal 795004, India
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8
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Liu P, Freeley M, Zarbakhsh A, Resmini M. Adsorption of soft NIPAM nanogels at hydrophobic and hydrophilic interfaces: Conformation of the interfacial layers determined by neutron reflectivity. J Colloid Interface Sci 2022; 623:337-347. [PMID: 35594592 DOI: 10.1016/j.jcis.2022.05.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 03/18/2022] [Accepted: 05/02/2022] [Indexed: 11/25/2022]
Abstract
The application of stimuli-responsive microgels and nanogels in drug delivery, catalysis, sensing, and coatings is restricted currently by the limited understanding of the factors influencing their adsorption dynamics and structural changes at interfaces. We have used neutron reflectivity to resolve, on the Ångström scale, the structure of 5% crosslinked N-isopropylacrylamide nanogels at both hydrophobic and hydrophilic interfaces in situ, as a function of temperature and bulk nanogel concentration. Our results show that the higher flexibility given by the low crosslinker content allows for a more ordered structure and packing. The adsorption of the thermoresponsive nanogels is primarily driven by temperature, more specifically its proximity to its volume phase transition temperature, while concentration plays a secondary role. Hydrophobic interactions drive the conformation of the first layer at the interface, which plays a key role in influencing the overall nanogel structure. The mobility of the first layer at the air-water interface as opposed to the interfacial confinement at the solid (SiC8)-liquid interface, results in a different conformation, a more compact and less deformed packing structure, which ultimately drives the structure of the subsequent layers. The evidence for the different structural conformations determined by the degree of hydrophobicity of the interface provides new knowledge, which is essential for the development of further applications. The key role of hydrophobic interactions in driving adsorption and interfacial behavior was also confirmed by fluid AFM experiments which visualized adherence of the nanogels to SiC8 modified surfaces.
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Affiliation(s)
- Pengfei Liu
- Department of Chemistry, SPCS, Queen Mary University of London, Mile End Road, London E1 4NS, UK
| | - Mark Freeley
- Department of Chemistry, SPCS, Queen Mary University of London, Mile End Road, London E1 4NS, UK
| | - Ali Zarbakhsh
- Department of Chemistry, SPCS, Queen Mary University of London, Mile End Road, London E1 4NS, UK.
| | - Marina Resmini
- Department of Chemistry, SPCS, Queen Mary University of London, Mile End Road, London E1 4NS, UK.
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9
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Fatemi SM, Fatemi SJ. A comparative study of the wetting behaviors on a rutile TiO2 having different surface morphologies. J Mol Graph Model 2022; 112:108123. [DOI: 10.1016/j.jmgm.2022.108123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 12/18/2021] [Accepted: 01/10/2022] [Indexed: 10/19/2022]
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10
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Jellicoe M, Igder A, Chuah C, Jones DB, Luo X, Stubbs KA, Crawley EM, Pye SJ, Joseph N, Vimalananthan K, Gardner Z, Harvey DP, Chen X, Salvemini F, He S, Zhang W, Chalker JM, Quinton JS, Tang Y, Raston CL. Vortex fluidic induced mass transfer across immiscible phases. Chem Sci 2022; 13:3375-3385. [PMID: 35432865 PMCID: PMC8943860 DOI: 10.1039/d1sc05829k] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Accepted: 01/30/2022] [Indexed: 12/03/2022] Open
Abstract
Mixing immiscible liquids typically requires the use of auxiliary substances including phase transfer catalysts, microgels, surfactants, complex polymers and nano-particles and/or micromixers. Centrifugally separated immiscible liquids of different densities in a 45° tilted rotating tube offer scope for avoiding their use. Micron to submicron size topological flow regimes in the thin films induce high inter-phase mass transfer depending on the nature of the two liquids. A hemispherical base tube creates a Coriolis force as a 'spinning top' (ST) topological fluid flow in the less dense liquid which penetrates the denser layer of liquid, delivering liquid from the upper layer through the lower layer to the surface of the tube with the thickness of the layers determined using neutron imaging. Similarly, double helical (DH) topological flow in the less dense liquid, arising from Faraday wave eddy currents twisted by Coriolis forces, impact through the less dense liquid onto the surface of the tube. The lateral dimensions of these topological flows have been determined using 'molecular drilling' impacting on a thin layer of polysulfone on the surface of the tube and self-assembly of nanoparticles at the interface of the two liquids. At high rotation speeds, DH flow also occurs in the denser layer, with a critical rotational speed reached resulting in rapid phase demixing of preformed emulsions of two immiscible liquids. ST flow is perturbed relative to double helical flow by changing the shape of the base of the tube while maintaining high mass transfer between phases as demonstrated by circumventing the need for phase transfer catalysts. The findings presented here have implications for overcoming mass transfer limitations at interfaces of liquids, and provide new methods for extractions and separation science, and avoiding the formation of emulsions.
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Affiliation(s)
- Matt Jellicoe
- Flinders Institute for Nanoscale Science and Technology, College of Science and Engineering, Flinders University Bedford Park SA 5042 Australia
| | - Aghil Igder
- Flinders Institute for Nanoscale Science and Technology, College of Science and Engineering, Flinders University Bedford Park SA 5042 Australia
| | - Clarence Chuah
- Flinders Institute for Nanoscale Science and Technology, College of Science and Engineering, Flinders University Bedford Park SA 5042 Australia
| | - Darryl B Jones
- Flinders Institute for Nanoscale Science and Technology, College of Science and Engineering, Flinders University Bedford Park SA 5042 Australia
| | - Xuan Luo
- Flinders Institute for Nanoscale Science and Technology, College of Science and Engineering, Flinders University Bedford Park SA 5042 Australia
| | - Keith A Stubbs
- School of Molecular Sciences, The University of Western Australia 35 Stirling Highway Crawley WA 6009 Australia
| | - Emily M Crawley
- Flinders Institute for Nanoscale Science and Technology, College of Science and Engineering, Flinders University Bedford Park SA 5042 Australia
| | - Scott J Pye
- Flinders Institute for Nanoscale Science and Technology, College of Science and Engineering, Flinders University Bedford Park SA 5042 Australia
| | - Nikita Joseph
- Flinders Institute for Nanoscale Science and Technology, College of Science and Engineering, Flinders University Bedford Park SA 5042 Australia
| | - Kasturi Vimalananthan
- Flinders Institute for Nanoscale Science and Technology, College of Science and Engineering, Flinders University Bedford Park SA 5042 Australia
| | - Zoe Gardner
- Flinders Institute for Nanoscale Science and Technology, College of Science and Engineering, Flinders University Bedford Park SA 5042 Australia
| | - David P Harvey
- Flinders Institute for Nanoscale Science and Technology, College of Science and Engineering, Flinders University Bedford Park SA 5042 Australia
| | - Xianjue Chen
- School of Environmental and Life Sciences, The University of Newcastle Callaghan New South Wales 2308 Australia
| | - Filomena Salvemini
- Australian Nuclear Science and Technology Organization New Illawara Road, Lucas Heights NSW Australia
| | - Shan He
- Flinders Institute for Nanoscale Science and Technology, College of Science and Engineering, Flinders University Bedford Park SA 5042 Australia
- Department of Food Science and Engineering, School of Chemistry Chemical Engineering, Guangzhou University Guangzhou 510006 China
| | - Wei Zhang
- Centre for Marine Bioproducts Development, College of Medicine and Public Health, Flinders University Adelaide SA 5042 Australia
| | - Justin M Chalker
- Flinders Institute for Nanoscale Science and Technology, College of Science and Engineering, Flinders University Bedford Park SA 5042 Australia
| | - Jamie S Quinton
- Flinders Institute for Nanoscale Science and Technology, College of Science and Engineering, Flinders University Bedford Park SA 5042 Australia
- Flinders Microscopy and Microanalysis (FMMA), College of Science and Engineering, Flinders University GPO Box 2100 Adelaide South Australia 5001 Australia
| | - Youhong Tang
- Flinders Institute for Nanoscale Science and Technology, College of Science and Engineering, Flinders University Bedford Park SA 5042 Australia
| | - Colin L Raston
- Flinders Institute for Nanoscale Science and Technology, College of Science and Engineering, Flinders University Bedford Park SA 5042 Australia
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11
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Guzmán E, Maestro A. Soft Colloidal Particles at Fluid Interfaces. Polymers (Basel) 2022; 14:polym14061133. [PMID: 35335463 PMCID: PMC8956102 DOI: 10.3390/polym14061133] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 03/08/2022] [Accepted: 03/10/2022] [Indexed: 02/01/2023] Open
Abstract
The assembly of soft colloidal particles at fluid interfaces is reviewed in the present paper, with emphasis on the particular case of microgels formed by cross-linked polymer networks. The dual polymer/colloid character as well as the stimulus responsiveness of microgel particles pose a challenge in their experimental characterization and theoretical description when adsorbed to fluid interfaces. This has led to a controversial and, in some cases, contradictory picture that cannot be rationalized by considering microgels as simple colloids. Therefore, it is necessary to take into consideration the microgel polymer/colloid duality for a physically reliable description of the behavior of the microgel-laden interface. In fact, different aspects related to the above-mentioned duality control the organization of microgels at the fluid interface, and the properties and responsiveness of the obtained microgel-laden interfaces. This works present a critical revision of different physicochemical aspects involving the behavior of individual microgels confined at fluid interfaces, as well as the collective behaviors emerging in dense microgel assemblies.
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Affiliation(s)
- Eduardo Guzmán
- Departamento de Química Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Ciudad Universitaria s/n, 28040 Madrid, Spain
- Instituto Pluridisciplinar, Universidad Complutense de Madrid, Paseo de Juan XXIII, 28040 Madrid, Spain
- Correspondence: (E.G.); (A.M.)
| | - Armando Maestro
- Centro de Física de Materiales (CSIC, UPV/EHU), Paseo Manuel de Lardizabal 5, 20018 San Sebastian, Spain
- IKERBASQUE—Basque Foundation for Science, Plaza Euskadi 5, 48009 Bilbao, Spain
- Correspondence: (E.G.); (A.M.)
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12
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Vialetto J, Nussbaum N, Bergfreund J, Fischer P, Isa L. Influence of the interfacial tension on the microstructural and mechanical properties of microgels at fluid interfaces. J Colloid Interface Sci 2022; 608:2584-2592. [PMID: 34774321 DOI: 10.1016/j.jcis.2021.10.186] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 10/21/2021] [Accepted: 10/29/2021] [Indexed: 10/19/2022]
Abstract
Microgels are soft colloidal particles constituted by cross-linked polymer networks with a high potential for applications. In particular, after adsorption at a fluid interface, interfacial tension provides two-dimensional (2D) confinement for microgel monolayers and drives the reconfiguration of the particles, enabling their deployment in foam and emulsion stabilization and in surface patterning for lithography, sensing and optical materials. However, most studies focus on systems of fluids with a high interfacial tension, e.g. alkanes/ or air/water interfaces, which imparts similar properties to the assembled monolayers. Here, instead, we compare two organic fluid phases, hexane and methyl tert-butyl ether, which have markedly different interfacial tension (γ) values with water and thus tune the deformation of adsorbed microgels. We rationalize how γ controls the single-particle morphology, which consequently modulates the structural and mechanical response of the monolayers at varying interfacial compression. Specifically, when γ is low, the microgels are less deformed within the interface plane and their polymer networks can rearrange more easily upon lateral compression, leading to softer monolayers. Selecting interfaces with different surface energy offers an additional control to customize the 2D assembly of soft particles, from the fine-tuning of particle size and interparticle spacing to the tailoring of mechanical properties.
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Affiliation(s)
- Jacopo Vialetto
- Laboratory for Soft Materials and Interfaces, Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 5, 8093 Zürich, Switzerland.
| | - Natalie Nussbaum
- Institute of Food, Nutrition and Health, ETH Zürich, Schmelzbergstrasse 7, 8092 Zürich, Switzerland
| | - Jotam Bergfreund
- Institute of Food, Nutrition and Health, ETH Zürich, Schmelzbergstrasse 7, 8092 Zürich, Switzerland
| | - Peter Fischer
- Institute of Food, Nutrition and Health, ETH Zürich, Schmelzbergstrasse 7, 8092 Zürich, Switzerland
| | - Lucio Isa
- Laboratory for Soft Materials and Interfaces, Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 5, 8093 Zürich, Switzerland.
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13
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Dan A, Agnihotri P, Bochenek S, Richtering W. Adsorption dynamics of thermoresponsive microgels with incorporated short oligo(ethylene glycol) chains at the oil-water interface. SOFT MATTER 2021; 17:6127-6139. [PMID: 34076021 DOI: 10.1039/d1sm00146a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Herein, we report a systematic study of the adsorption behaviour of short oligo(ethylene glycol) (OEG) chains incorporated into poly(N-isopropylaccrylamide) (PNIPAM) microgels at the dodecane-water interface as a function of the microgel concentration at two different temperatures: 298 and 313 K. The dynamic interfacial tension of the interface for the adsorption of these functional microgels is measured by means of a pendent drop method. We find that similar to pure PNIPAM microgels, the functionalized microgels initially get transported from the bulk to the interface, where they undergo the deformability dependent spreading process, and thus leading to a reduction of interfacial tension. However, the OEG chains significantly influence the dynamic processes of the microgels at the interface, enabling precise control over the interfacial activity. A tuneability of adsorption behaviour that is interpreted in terms of the diversity of structural and morphological features of the microgels, can be achieved by changing the temperature and/or the OEG chain length of the comonomer. While the temperature induced phase transition generally slows down the adsorption kinetics of the microgels, increasing the temperature from 298 to 313 K allows faster reduction of interfacial tension for the adsorption of the microgels with long OEG chains among the studied comonomers, making them a unique interfacially active functional material. Overall, incorporation of OEG chains allows tailoring the interfacial activity of microgels, thereby paving the way for the use of these microgels to act as effective Pickering emulsion stabilizers in a range of applications.
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Affiliation(s)
- Abhijit Dan
- Department of Chemistry and Centre for Advanced Studies in Chemistry, Panjab University - Chandigarh, Sector 14, Chandigarh 160014, India.
| | - Priyanshi Agnihotri
- Department of Chemistry and Centre for Advanced Studies in Chemistry, Panjab University - Chandigarh, Sector 14, Chandigarh 160014, India.
| | - Steffen Bochenek
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany
| | - Walter Richtering
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany
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Pickering emulsions stabilized by thermoresponsive oligo(ethylene glycol)-based microgels: Effect of temperature-sensitivity on emulsion stability. J Colloid Interface Sci 2021; 589:96-109. [DOI: 10.1016/j.jcis.2020.12.082] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 12/21/2020] [Accepted: 12/22/2020] [Indexed: 01/20/2023]
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15
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Kozhunova EY, Rudyak VY, Li X, Shibayama M, Peters GS, Vyshivannaya OV, Nasimova IR, Chertovich AV. Microphase separation of stimuli-responsive interpenetrating network microgels investigated by scattering methods. J Colloid Interface Sci 2021; 597:297-305. [PMID: 33872886 DOI: 10.1016/j.jcis.2021.03.178] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2020] [Revised: 03/29/2021] [Accepted: 03/31/2021] [Indexed: 11/26/2022]
Abstract
Polymer stimuli-responsive microgels find their use in various applications. The knowledge of its internal structure is of importance for further improvement and expanding the scope. Interpenetrating network (IPN) microgels may possess a remarkable feature of strongly non-uniform inner architecture, even microphase separation, in conditions of a selective solvent. In this research, we, for the first time, use a combination of static light scattering (SLS) and small-angle X-ray scattering (SAXS) techniques to collect the structure factors of aqueous dispersions of poly(N-isopropylacrylamide)-polyacrylic acid IPN microgels on the broad scale ofqvalues. We study the influence of solvent quality on microgel conformations and show that in a selective solvent, such a system undergoes microphase separation: the sub-network in a poor solvent conditions forms dense small aggregates inside the large swollen sub-network in a good solvent. We propose the microstructured sphere model for the IPN microgel structure factor interpretation and perform additional analysis and verification through coarse-grained molecular dynamics computer simulations.
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Affiliation(s)
- Elena Yu Kozhunova
- Faculty of Physics, Lomonosov Moscow State University, Moscow 119991, Russia.
| | - Vladimir Yu Rudyak
- Faculty of Physics, Lomonosov Moscow State University, Moscow 119991, Russia.
| | - Xiang Li
- Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan.
| | - Mitsuhiro Shibayama
- Comprehensive Research Organization for Science and Society, Tokai, Ibaraki 319-1106, Japan.
| | - Georgy S Peters
- National Research Centre "Kurchatov Institute", Akademika Kurchatova pl., 1, Moscow 123182, Russian Federation
| | - Oxana V Vyshivannaya
- A.N. Nesmeyanov Institute of Organoelement Compounds of Russian Academy of Sciences, 119991 Moscow, Russia.
| | - Irina R Nasimova
- Russian Academy of Science, Moscow 119991, Russia; Faculty of Physics, Lomonosov Moscow State University, Moscow 119991, Russia.
| | - Alexander V Chertovich
- Semenov Federal Research Center for Chemical Physics, Moscow 119991, Russia; Faculty of Physics, Lomonosov Moscow State University, Moscow 119991, Russia.
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Bochenek S, Scotti A, Richtering W. Temperature-sensitive soft microgels at interfaces: air-water versus oil-water. SOFT MATTER 2021; 17:976-988. [PMID: 33284940 DOI: 10.1039/d0sm01774d] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The formation of smart emulsions or foams whose stability can be controlled on-demand by switching external parameters is of great interest for basic research and applications. An emerging group of smart stabilizers are microgels, which are nano- and micro-sized, three-dimensional polymer networks that are swollen by a good solvent. In the last decades, the influence of various external stimuli on the two-dimensional phase behavior of microgels at air- and oil-water interfaces has been studied. However, the impact of the top-phase itself has been barely considered. Here, we present data that directly address the influence of the top-phase on the microgel properties at interfaces. The dimensions of pNIPAM microgels are measured after deposition from two interfaces, i.e., air- and decane-water. While the total in-plane size of the microgel increases with increasing interfacial tension, the portions or fractions of the microgels situated in the aqueous phase are not affected. We correlate the area microgels occupy to the surface tensions of the interfaces, which allows to estimate an elastic modulus. In comparison to nanoindentation measurements, we observe a larger elastic modulus for the microgels. By combining compression, deposition, and visualization, we show that the two-dimensional phase behavior of the microgel monolayers is not altered, although the microgels have a larger total in-plane size at higher interfacial tension.
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Affiliation(s)
- Steffen Bochenek
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany.
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17
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Microgels self-assembly at liquid/liquid interface as stabilizers of emulsion: Past, present & future. Adv Colloid Interface Sci 2021; 287:102333. [PMID: 33360120 DOI: 10.1016/j.cis.2020.102333] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2020] [Revised: 11/25/2020] [Accepted: 11/27/2020] [Indexed: 12/22/2022]
Abstract
The most recent developments on Pickering emulsions deal with the design of responsive emulsions able to undergo fast destabilization under the effect of an external stimulus. In this scenario, soft colloidal particles like microgels are considered novel class suitable emulsifiers. Microgels particles self-assemblies are highly deformable at interfaces covering higher surfaces than hard particles and their interfacial behavior strongly depends on external-stimuli. Microgels are very diverse owing to the large variety of them from the point of view of possible combinations of stimuli-responsiveness and different microstructures (crosslinking density and distribution). Herein, we illustrate the use of different types of responsive microgels not only from a structural point of view but also even from physical one. For that, the effect of different microgels parameters such as internal structure and charge density on mechanical properties of the interface will be discussed.
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Lenzi V, Ramos MMD, Marques LSA. Dissipative particle dynamics simulations of end-cross-linked nanogels. MOLECULAR SIMULATION 2020. [DOI: 10.1080/08927022.2020.1859111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- Veniero Lenzi
- Center of Physics of Universities of Minho and Porto, University of Minho, Campus de Gualtar, Braga, Portugal
| | - Marta M. D. Ramos
- Center of Physics of Universities of Minho and Porto, University of Minho, Campus de Gualtar, Braga, Portugal
| | - Luís S. A. Marques
- Center of Physics of Universities of Minho and Porto, University of Minho, Campus de Gualtar, Braga, Portugal
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Mehrabian H, Snoeijer JH, Harting J. Desorption energy of soft particles from a fluid interface. SOFT MATTER 2020; 16:8655-8666. [PMID: 32857082 DOI: 10.1039/d0sm01122c] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The efficiency of soft particles to stabilize emulsions is examined by measuring their desorption free energy, i.e., the mechanical work required to detach the particle from a fluid interface. Here, we consider rubber-like elastic as well as microgel particles, using coarse-grained molecular dynamics simulations. The energy of desorption is computed for two and three-dimensional configurations by means of the mean thermodynamic integration method. It is shown that the softness affects the particle-interface binding in two opposing directions as compared to rigid particles. On the one hand, a soft particle spreads at the interface and thereby removes a larger unfavorable liquid-liquid contact area compared to rigid particles. On the other hand, softness provides the particle with an additional degree of freedom to get reshaped instead of deforming the interface, resulting in a smaller restoring force during the detachment. It is shown that the first effect prevails so that a soft spherical particle attaches to the fluid interface more strongly than rigid spheres. Finally, we consider microgel particles both in the swollen and in the collapsed state. Surprisingly, we find that the latter has a larger binding energy. All results are rationalised using thermodynamic arguments and thereby offer detailed insights into the desorption energy of soft particles from fluid interfaces.
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Affiliation(s)
- Hadi Mehrabian
- Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands and Physics of Fluids Group and J. M. Burgers Centre for Fluid Dynamics, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands and Chemical Engineering Department, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Jacco H Snoeijer
- Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands and Physics of Fluids Group and J. M. Burgers Centre for Fluid Dynamics, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Jens Harting
- Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands and Physics of Fluids Group and J. M. Burgers Centre for Fluid Dynamics, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands and Helmholtz-Institute Erlangen-Nürnberg for Renewable Energy, Forschungszentrum Jülich, Fürther Str. 248, 90429 Nürnberg, Germany. and Department of Chemical and Biological Engineering and Department of Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Fürther Straße 248, 90429 Nürnberg, Germany
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Schmidt MM, Bochenek S, Gavrilov AA, Potemkin II, Richtering W. Influence of Charges on the Behavior of Polyelectrolyte Microgels Confined to Oil-Water Interfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:11079-11093. [PMID: 32845643 DOI: 10.1021/acs.langmuir.0c02081] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The role of electrostatics on the interfacial properties of polyelectrolyte microgels has been discussed controversially in the literature. It is not yet clear if, or how, Coulomb interactions affect their behavior under interfacial confinement. In this work, we combine compression isotherms, atomic force microscopy imaging, and computer simulations to further investigate the behavior of pH-responsive microgels at oil-water interfaces. At low compression, charged microgels can be compressed more than uncharged microgels. The in-plane effective area of charged microgels is found to be smaller in comparison to uncharged ones. Thus, the compressibility is governed by in-plane interactions of the microgels with the interface. At high compression, however, charged microgels are less compressible than uncharged microgels. Microgel fractions located in the aqueous phase interact earlier for charged than for uncharged microgels because of their different swelling perpendicular to the interface. Therefore, the compressibility at high compression is controlled by out-of-plane interactions. In addition, the size of the investigated microgels plays a pivotal role. The charge-dependent difference in compressibility at low compression is only observed for small but not for large microgels, while the behavior at high compression does not depend on the size. Our results highlight the complex nature of soft polymer microgels as compared to rigid colloidal particles. We clearly demonstrate that electrostatic interactions affect the interfacial properties of polyelectrolyte microgels.
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Affiliation(s)
| | - Steffen Bochenek
- Institute of Physical Chemistry, RWTH Aachen University, 52074 Aachen, Germany
| | - Alexey A Gavrilov
- Physics Department, Lomonosov Moscow State University, Moscow 119991, Russian Federation
| | - Igor I Potemkin
- Physics Department, Lomonosov Moscow State University, Moscow 119991, Russian Federation
- DWI - Leibniz Institute for Interactive Materials, 52074 Aachen, Germany
- National Research South Ural State University, Chelyabinsk 454080, Russian Federation
| | - Walter Richtering
- Institute of Physical Chemistry, RWTH Aachen University, 52074 Aachen, Germany
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Gavrilov AA, Rudyak VY, Chertovich AV. Computer simulation of the core-shell microgels synthesis via precipitation polymerization. J Colloid Interface Sci 2020; 574:393-398. [DOI: 10.1016/j.jcis.2020.04.064] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 04/14/2020] [Accepted: 04/16/2020] [Indexed: 01/21/2023]
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Choudhury CK, Palkar V, Kuksenok O. Computational Design of Nanostructured Soft Interfaces: Focus on Shape Changes and Spreading of Cubic Nanogels. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:7109-7123. [PMID: 31927898 DOI: 10.1021/acs.langmuir.9b03486] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Understanding the dynamics of gels at soft interfaces is vital for a range of applications, from biocatalysis and drug delivery to enhanced oil recovery applications. Herein, we use dissipative particle dynamics simulations to focus on the shape changes of a cubic nanogel as it adsorbs from the aqueous phase onto the oil-water interface, effectively acting as a compatibilizer. Upon adsorption at the interface, the hydrogel spreads over the interface, adopting various shapes depending on its size and cross-link density. We characterize these shapes by the shape anisotropy and an effective extent of spreading. We highlight the differences between these characteristics for cubic and spherical nanogels and show that the choice of the cubic shape over the spherical one results in a wider range of topographies that could be dynamically prescribed onto the soft interface due to the gels' adsorption. We first validate our model parameters with respect to the known experimental values for polyacrylamide (PAAm) gels and focus on spreading and shape changes of PAAm nanogels onto the oil-water interfaces. We then probe the behavior of active gels by changing an affinity of the polymer matrix for the solvent, which can be caused by the application of an external stimulus (light, temperature, or change in the chemical composition of solvent). Furthermore, we focus on the interactions between multiple gels placed at the liquid-liquid interface. We show that controlling the shapes and the clustering of the gels at the interfaces via variations in solvent quality result in tailoring the dynamics and topography of soft nanostructured interfaces. Hence, our findings provide insights into the design of soft active nanostructured interfaces with topographies controlled externally via solvent quality.
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Affiliation(s)
- Chandan Kumar Choudhury
- Department of Materials Science and Engineering, Clemson University, Clemson, South Carolina 29634, United States
| | - Vaibhav Palkar
- Department of Materials Science and Engineering, Clemson University, Clemson, South Carolina 29634, United States
| | - Olga Kuksenok
- Department of Materials Science and Engineering, Clemson University, Clemson, South Carolina 29634, United States
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Arismendi-Arrieta DJ, Moreno AJ. Deformability and solvent penetration in soft nanoparticles at liquid-liquid interfaces. J Colloid Interface Sci 2020; 570:212-222. [DOI: 10.1016/j.jcis.2020.02.102] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 02/24/2020] [Accepted: 02/25/2020] [Indexed: 12/29/2022]
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Anakhov MV, Gumerov RA, Richtering W, Pich A, Potemkin II. Scavenging One of the Liquids versus Emulsion Stabilization by Microgels in a Mixture of Two Immiscible Liquids. ACS Macro Lett 2020; 9:736-742. [PMID: 35648562 DOI: 10.1021/acsmacrolett.0c00191] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
It is known that microgels can serve as soft, permeable and stimuli-responsive alternative of solid colloidal particles to stabilize oil-water emulsions. The driving force for the adsorption of the microgels on interface of two immiscible liquids is a shielding of unfavorable oil-water contacts by adsorbed subchains, that is, the decrease of the surface tension between the liquids. Such phenomenon usually proceeds if volume fractions of the two liquids are comparable with each other and the microgel concentration is not high enough. The natural question arises: what is going on with the system in the opposite case of strongly asymmetric mixture (one of the liquids (oil) has a very small fraction) or high microgel concentration (the overall volume of the microgels exceeds the volume of the minor oil component)? Here we demonstrate that the microgels uptake the oil whose concentration within the microgels can be orders of magnitude higher than outside, leading to the additional microgel swelling (in comparison with the swelling in water). Thus, the microgels can serve as scavengers and concentrators of liquids dissolved in water. At first glance, this effect seems counterintuitive. However, it has a clear physical reason related to the incompatibility of oil and water. Absorption of the oil by microgels reduces unfavorable oil-water contacts by microgel segments: the microgels have a higher concentration of the segments at the periphery, forming a shell. The microgels with uptaken oil are stable toward aggregation at very small oil concentration in the mixture. However, an increase in the oil concentration can lead to aggregation of the microgels into dimers, trimers, and so on. The increasing concentration of oil mediates the attraction between the microgels: the oil in the aggregates appears to be localized in-between the microgels instead of their interior, which is accompanied by the release of the elastic stress of the microgels. A further increase in the oil concentration results in a growth of the size of the oil droplets between the microgels and the number of the microgels at the droplet's periphery, that is, the emulsion is formed.
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Affiliation(s)
- Mikhail V. Anakhov
- Physics Department, Lomonosov Moscow State University, Leninskie Gory 1-2, Moscow 119991, Russian Federation
| | - Rustam A. Gumerov
- Physics Department, Lomonosov Moscow State University, Leninskie Gory 1-2, Moscow 119991, Russian Federation
- DWI - Leibniz Institute for Interactive Materials e.V., Forckenbeckstraße 50, Aachen 52056, Germany
| | - Walter Richtering
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, Aachen 52056, Germany
| | - Andrij Pich
- DWI - Leibniz Institute for Interactive Materials e.V., Forckenbeckstraße 50, Aachen 52056, Germany
- Institute of Technical and Macromolecular Chemistry, RWTH Aachen University, Worringerweg 2, 52074, Aachen, Germany
- Aachen Maastricht Institute for Biobased Materials (AMIBM), Maastricht University, Urmonderbaan 22, 6167 RD Geleen, The Netherlands
| | - Igor I. Potemkin
- Physics Department, Lomonosov Moscow State University, Leninskie Gory 1-2, Moscow 119991, Russian Federation
- DWI - Leibniz Institute for Interactive Materials e.V., Forckenbeckstraße 50, Aachen 52056, Germany
- National Research South Ural State University, Chelyabinsk 454080, Russian Federation
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Bushuev NV, Gumerov RA, Bochenek S, Pich A, Richtering W, Potemkin II. Compression and Ordering of Microgels in Monolayers Formed at Liquid-Liquid Interfaces: Computer Simulation Studies. ACS APPLIED MATERIALS & INTERFACES 2020; 12:19903-19915. [PMID: 32248678 DOI: 10.1021/acsami.0c01600] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Monolayers of polymer microgels adsorbed at the liquid interfaces were studied by dissipative particle dynamics simulations. The results demonstrated that the compressibility of the monolayers can be widely tuned by varying the cross-linking density of the microgels and their (in)compatibility with the immiscible liquids. In particular, the compression of the monolayers (increase of 2D concentration of the microgels) leads to the decrease of their lateral size. Herewith, the shape of the individual soft particles gradually changes from oblate (diluted 2D system) to nearly spherical (compressed monolayer). The polymer concentration profiles plotted along the normal to the interface reveal a nonmonotonous shape with a sharp maximum at the interface. This is a consequence of the shielding effect: saturation of the interface by monomer units of the subchains is driven by minimization of unfavorable contacts between the immiscible liquids and is opposed by elasticity of the network. The decrease of the interfacial tension upon concentration (compression) of the monolayer is quantified. It has been demonstrated that the interfacial tension significantly differs if the solubility of the polymer chains of the microgel network in the liquids changes. These results correlate well with experimental data. The examination of the microgels' crystalline ordering in monolayers demonstrated a nonmonotonous dependency on the compression degree (microgel concentration). Finally, the worsening of the solvent quality leads to the collapse of the microgels in monolayer and nonmonotonous behavior of the interfacial tension.
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Affiliation(s)
- Nikita V Bushuev
- Physics Department, Lomonosov Moscow State University, Leninskie Gory 1-2, Moscow 119991, Russian Federation
| | - Rustam A Gumerov
- Physics Department, Lomonosov Moscow State University, Leninskie Gory 1-2, Moscow 119991, Russian Federation
- DWI-Leibniz Institute for Interactive Materials e.V., Forckenbeckstraße 50, Aachen 52056, Germany
| | - Steffen Bochenek
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, Aachen 52056, Germany
| | - Andrij Pich
- DWI-Leibniz Institute for Interactive Materials e.V., Forckenbeckstraße 50, Aachen 52056, Germany
- Aachen Maastricht Institute for Biobased Materials (AMIBM), Maastricht University, Urmonderbaan 22, Geleen 6167 RD, The Netherlands
| | - Walter Richtering
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, Aachen 52056, Germany
| | - Igor I Potemkin
- Physics Department, Lomonosov Moscow State University, Leninskie Gory 1-2, Moscow 119991, Russian Federation
- DWI-Leibniz Institute for Interactive Materials e.V., Forckenbeckstraße 50, Aachen 52056, Germany
- National Research South Ural State University, Chelyabinsk 454080, Russian Federation
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Gumerov RA, Gau E, Xu W, Melle A, Filippov SA, Sorokina AS, Wolter NA, Pich A, Potemkin II. Amphiphilic PVCL/TBCHA microgels: From synthesis to characterization in a highly selective solvent. J Colloid Interface Sci 2020; 564:344-356. [DOI: 10.1016/j.jcis.2019.12.123] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2019] [Revised: 12/26/2019] [Accepted: 12/27/2019] [Indexed: 10/25/2022]
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Rey M, Fernandez-Rodriguez MA, Karg M, Isa L, Vogel N. Poly- N-isopropylacrylamide Nanogels and Microgels at Fluid Interfaces. Acc Chem Res 2020; 53:414-424. [PMID: 31940173 DOI: 10.1021/acs.accounts.9b00528] [Citation(s) in RCA: 68] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The confinement of colloidal particles at liquid interfaces offers many opportunities for materials design. Adsorption is driven by a reduction of the total free energy as the contact area between the two liquids is partially replaced by the particle. From an application point of view, particle-stabilized interfaces form emulsions and foams with superior stability. Liquid interfaces also effectively confine colloidal particles in two dimensions and therefore provide ideal model systems to fundamentally study particle interactions, dynamics, and self-assembly. With progress in the synthesis of nanomaterials, more and more complex and functional particles are available for such studies. In this Account, we focus on poly(N-isopropylacrylamide) nanogels and microgels. These are cross-linked polymeric particles that swell and soften by uptaking large amounts of water. The incorporated water can be partially expelled, causing a volume phase transition into a collapsed state when the temperature is increased above approximately 32 °C. Soft microgels adsorbed to liquid interfaces significantly deform under the influence of interfacial tension and assume cross sections exceeding their bulk dimensions. In particular, a pronounced corona forms around the microgel core, consisting of dangling chains at the microgel periphery. These polymer chains expand at the interface and strongly affect the interparticle interactions. The particle deformability therefore leads to a significantly more complex interfacial phase behavior that provides a rich playground to explore structure formation processes. We first discuss the characteristic "fried-egg" or core-corona morphology of individual microgels adsorbed to a liquid interface and comment on the dependence of this interfacial morphology on their physicochemical properties. We introduce different theoretical models to describe their interfacial morphology. In a second part, we introduce how ensembles of microgels interact and self-assemble at liquid interfaces. The core-corona morphology and the possibility to force these elements into overlap upon compression results in a complex phase behavior with a phase transition between microgels with extended and collapsed coronae. We discuss the influence of the internal particle architecture, also including core-shell microgels with rigid cores, on the phase behavior. Finally, we present new routes for the realization of more complex structures, resulting from multiple deposition protocols and from engineering the interaction potential of the individual particles.
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Affiliation(s)
- Marcel Rey
- Institute of Particle Technology (LFG), Friedrich-Alexander University Erlangen-Nürnberg, Cauerstrasse 4, 91058 Erlangen, Germany
- Interdisciplinary Center for Functional Particle Systems (FPS), Friedrich-Alexander University Erlangen-Nürnberg, Haberstrasse 9a, 91058 Erlangen, Germany
| | - Miguel Angel Fernandez-Rodriguez
- Laboratory for Soft Materials and Interfaces, Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 5, 8093 Zürich, Switzerland
| | - Matthias Karg
- Institut für Physikalische Chemie I: Kolloide und Nanooptik, Heinrich-Heine-Universität Düsseldorf, Universitätsstrasse 1, D-40225 Düsseldorf, Germany
| | - Lucio Isa
- Laboratory for Soft Materials and Interfaces, Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 5, 8093 Zürich, Switzerland
| | - Nicolas Vogel
- Institute of Particle Technology (LFG), Friedrich-Alexander University Erlangen-Nürnberg, Cauerstrasse 4, 91058 Erlangen, Germany
- Interdisciplinary Center for Functional Particle Systems (FPS), Friedrich-Alexander University Erlangen-Nürnberg, Haberstrasse 9a, 91058 Erlangen, Germany
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Parisi D, Ruan Y, Ochbaum G, Silmore KS, Cullari LL, Liu CY, Bitton R, Regev O, Swan JW, Loppinet B, Vlassopoulos D. Short and Soft: Multidomain Organization, Tunable Dynamics, and Jamming in Suspensions of Grafted Colloidal Cylinders with a Small Aspect Ratio. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:17103-17113. [PMID: 31793788 DOI: 10.1021/acs.langmuir.9b03025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The yet virtually unexplored class of soft colloidal rods with a small aspect ratio is investigated and shown to exhibit a very rich phase and dynamic behavior, spanning from liquid to nearly melt state. Instead of the nematic order, these short and soft nanocylinders alter their organization with increasing concentration from isotropic liquid with random orientation to small domains with preferred local orientation and eventually a multidomain arrangement with a local orientational order. The latter gives rise to a kinetically suppressed state akin to structural glass with detectable terminal relaxation, which, on further increasing concentration, reveals features of hexagonally packed order as in ordered block copolymers. The respective dynamic response comprises four regimes, all above the overlapping concentration of 0.02 g/mL:(I) from 0.03 to 0.1 g/mol, the system undergoes a liquid-to-solidlike transition with a structural relaxation time that grows by 4 orders of magnitude. (II) From 0.1 to 0.2 g/mL, a dramatic slowing-down is observed and is accompanied by an evolution from isotropic to a multidomain structure. (III) Between 0.2 and 0.6 g/mol, the suspensions exhibit signatures of shell interpenetration and jamming, with the colloidal plateau modulus depending linearly on concentration. (IV) At 0.74 g/mL, in the densely jammed state, the viscoelastic signature of hexagonally packed cylinders from microphase-separated block copolymers is detected. These properties set short and soft nanocylinders apart from long colloidal rods (with a large aspect ratio) and provide insights for fundamentally understanding the physics in this intermediate soft colloidal regime and for tailoring the flow properties of nonspherical soft colloids.
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Affiliation(s)
- Daniele Parisi
- Institute of Electronic Structure & Laser, FORTH , Heraklion 71110 , Crete , Greece
- Department of Materials Science & Technology , University of Crete , Heraklion 71003 , Crete , Greece
| | - Yingbo Ruan
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Engineering Plastics, Institute of Chemistry , The Chinese Academy of Sciences , Beijing 100190 , China
- University of Chinese Academy of Sciences , Beijing 100049 , China
| | - Guy Ochbaum
- Department of Chemical Engineering and the Ilze Katz Institute for Nanoscale Science & Technology , Ben-Gurion University of the Negev , Beer-Sheva 84105 , Israel
| | - Kevin S Silmore
- Department of Chemical Engineering , Massachusetts Institute of Technology , Cambridge 02139 , Massachusetts , United States
| | - Lucas L Cullari
- Department of Chemical Engineering and the Ilze Katz Institute for Nanoscale Science & Technology , Ben-Gurion University of the Negev , Beer-Sheva 84105 , Israel
| | - Chen-Yang Liu
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Engineering Plastics, Institute of Chemistry , The Chinese Academy of Sciences , Beijing 100190 , China
- University of Chinese Academy of Sciences , Beijing 100049 , China
| | - Ronit Bitton
- Department of Chemical Engineering and the Ilze Katz Institute for Nanoscale Science & Technology , Ben-Gurion University of the Negev , Beer-Sheva 84105 , Israel
| | - Oren Regev
- Department of Chemical Engineering and the Ilze Katz Institute for Nanoscale Science & Technology , Ben-Gurion University of the Negev , Beer-Sheva 84105 , Israel
| | - James W Swan
- Department of Chemical Engineering , Massachusetts Institute of Technology , Cambridge 02139 , Massachusetts , United States
| | - Benoit Loppinet
- Institute of Electronic Structure & Laser, FORTH , Heraklion 71110 , Crete , Greece
| | - Dimitris Vlassopoulos
- Institute of Electronic Structure & Laser, FORTH , Heraklion 71110 , Crete , Greece
- Department of Materials Science & Technology , University of Crete , Heraklion 71003 , Crete , Greece
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Bochenek S, Scotti A, Ogieglo W, Fernández-Rodríguez MÁ, Schulte MF, Gumerov RA, Bushuev NV, Potemkin II, Wessling M, Isa L, Richtering W. Effect of the 3D Swelling of Microgels on Their 2D Phase Behavior at the Liquid-Liquid Interface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:16780-16792. [PMID: 31782927 DOI: 10.1021/acs.langmuir.9b02498] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We investigate soft, temperature-sensitive microgels at fluid interfaces. Though having an isotropic, spherical shape in bulk solution, the microgels become anisotropic upon adsorption. The structure of microgels at interfaces is described by a core-corona morphology. Here, we investigate how changing temperature across the microgel volume phase transition temperature, which leads to swelling/deswelling of the microgels in the aqueous phase, affects the phase behavior within the monolayer. We combine compression isotherms, atomic force microscopy imaging, multiwavelength ellipsometry, and computer simulations. At low compression, the interaction between adsorbed microgels is dominated by their highly stretched corona and the phase behavior of the microgel monolayers is the same. The polymer segments within the interface lose their temperature-sensitivity because of the strong adsorption to the interface. At high compression, however, the portions of the microgels that are located in the aqueous side of the interface become relevant and prevail in the microgel interactions. These portions are able to collapse and, consequently, the isostructural phase transition is altered. Thus, the temperature-dependent swelling perpendicular to the interface ("3D") affects the compressibility parallel to the interface ("2D"). Our results highlight the distinctly different behavior of soft, stimuli-sensitive microgels as compared to rigid nanoparticles.
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Affiliation(s)
- Steffen Bochenek
- Institute of Physical Chemistry , RWTH Aachen University , Landoltweg 2 , 52056 Aachen , Germany
| | - Andrea Scotti
- Institute of Physical Chemistry , RWTH Aachen University , Landoltweg 2 , 52056 Aachen , Germany
| | - Wojciech Ogieglo
- Chemical Process Engineering , RWTH Aachen University , Forckenbeckstrasse 51 , 52064 Aachen , Germany
| | - Miguel Ángel Fernández-Rodríguez
- Laboratory for Soft Materials and Interfaces, Department of Materials , ETH Zurich , Vladimir-Prelog-Weg 1-5/10 , 8093 Zurich , Switzerland
| | - M Friederike Schulte
- Institute of Physical Chemistry , RWTH Aachen University , Landoltweg 2 , 52056 Aachen , Germany
| | - Rustam A Gumerov
- Physics Department , Lomonosov Moscow State University , Moscow 119991 , Russian Federation
- DWI-Leibniz Institute for Interactive Materials , Forckenbeckstrasse 50 , Aachen 52056 , Germany
| | - Nikita V Bushuev
- Physics Department , Lomonosov Moscow State University , Moscow 119991 , Russian Federation
| | - Igor I Potemkin
- Physics Department , Lomonosov Moscow State University , Moscow 119991 , Russian Federation
- DWI-Leibniz Institute for Interactive Materials , Forckenbeckstrasse 50 , Aachen 52056 , Germany
- National Research South Ural State University , Chelyabinsk 454080 , Russian Federation
| | - Matthias Wessling
- Chemical Process Engineering , RWTH Aachen University , Forckenbeckstrasse 51 , 52064 Aachen , Germany
- DWI-Leibniz Institute for Interactive Materials , Forckenbeckstrasse 50 , Aachen 52056 , Germany
| | - Lucio Isa
- Laboratory for Soft Materials and Interfaces, Department of Materials , ETH Zurich , Vladimir-Prelog-Weg 1-5/10 , 8093 Zurich , Switzerland
| | - Walter Richtering
- Institute of Physical Chemistry , RWTH Aachen University , Landoltweg 2 , 52056 Aachen , Germany
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Hoppe Alvarez L, Eisold S, Gumerov RA, Strauch M, Rudov AA, Lenssen P, Merhof D, Potemkin II, Simon U, Wöll D. Deformation of Microgels at Solid-Liquid Interfaces Visualized in Three-Dimension. NANO LETTERS 2019; 19:8862-8867. [PMID: 31642321 DOI: 10.1021/acs.nanolett.9b03688] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Solid-liquid interfaces play an important role for functional devices. Hence, a detailed understanding of the interaction of soft matter objects with solid supports and of the often concomitant structural deformations is of great importance. We address this topic in a combined experimental and simulation approach. We investigated thermoresponsive poly(N-isopropylmethacrylamide) microgels (μGs) at different surfaces in an aqueous environment. As super-resolution fluorescence imaging method, three-dimensional direct stochastical optical reconstruction microscopy (dSTORM) allowed for visualizing μGs in their three-dimensional (3D) shape, for example, in a "fried-egg" conformation depending on the hydrophilicity of the surface (strength of adsorption). The 3D shape, as defined by point clouds obtained from single-molecule localizations, was analyzed. A new fitting algorithm yielded an isosurface of constant density which defines the deformation of μGs at the different surfaces. The presented methodology quantifies deformation of objects with fuzzy surfaces and allows for comparison of their structures, whereby it is completely independent from the data acquisition method. Finally, the experimental data are complemented with mesoscopic computer simulations in order to (i) rationalize the experimental results and (ii) to track the evolution of the shape with changing surface hydrophilicity; a good correlation of the shapes obtained experimentally and with computer simulations was found.
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Affiliation(s)
- Laura Hoppe Alvarez
- Institute of Physical Chemistry , RWTH Aachen University , Landoltweg 2 , D-52056 Aachen , Germany
| | - Sabine Eisold
- Institute of Inorganic Chemistry , RWTH Aachen University , Landoltweg 1 a , D-52056 Aachen , Germany
| | - Rustam A Gumerov
- Physics Department , Lomonosov Moscow State University , Leninskie Gory 1-2 , Moscow 119991 , Russian Federation
- DWI - Leibniz-Institute for Interactive Materials , Forckenbeckstraße 50 , D-52056 Aachen , Germany
| | - Martin Strauch
- Institute of Imaging and Computer Vision , RWTH Aachen University , Kopernikusstraße 16 , 52074 Aachen , Germany
| | - Andrey A Rudov
- Physics Department , Lomonosov Moscow State University , Leninskie Gory 1-2 , Moscow 119991 , Russian Federation
- DWI - Leibniz-Institute for Interactive Materials , Forckenbeckstraße 50 , D-52056 Aachen , Germany
| | - Pia Lenssen
- Institute of Physical Chemistry , RWTH Aachen University , Landoltweg 2 , D-52056 Aachen , Germany
| | - Dorit Merhof
- Institute of Imaging and Computer Vision , RWTH Aachen University , Kopernikusstraße 16 , 52074 Aachen , Germany
| | - Igor I Potemkin
- Physics Department , Lomonosov Moscow State University , Leninskie Gory 1-2 , Moscow 119991 , Russian Federation
- DWI - Leibniz-Institute for Interactive Materials , Forckenbeckstraße 50 , D-52056 Aachen , Germany
- National Research South Ural State University , Chelyabinsk 454080 , Russian Federation
| | - Ulrich Simon
- Institute of Inorganic Chemistry , RWTH Aachen University , Landoltweg 1 a , D-52056 Aachen , Germany
| | - Dominik Wöll
- Institute of Physical Chemistry , RWTH Aachen University , Landoltweg 2 , D-52056 Aachen , Germany
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32
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Tatry MC, Qiu Y, Lapeyre V, Garrigue P, Schmitt V, Ravaine V. Sugar-responsive Pickering emulsions mediated by switching hydrophobicity in microgels. J Colloid Interface Sci 2019; 561:481-493. [PMID: 31740129 DOI: 10.1016/j.jcis.2019.11.023] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Revised: 11/06/2019] [Accepted: 11/06/2019] [Indexed: 12/16/2022]
Abstract
HYPOTHESIS Pickering emulsions stabilized by soft and responsive microgels can demulsify on demand upon microgel collapse. The concept has been explored with simple model microgels such as poly(N-isopropylacrylamide) (pNIPAM) and their derivatives, but the role of functionalization is largely unexplored. EXPERIMENTS Saccharide-responsive phenylboronic-modified microgels are used as Pickering emulsion stabilizers. Emulsion stability and microgel organization at drop surface are studied as a function of saccharide concentration. Better insight into their behavior at interfaces is gained through adsorption kinetics and Langmuir film studies at air-water interface. FINDINGS The functionalization of water-swollen microgels by phenylboronic functions imparts some hydrophobicity to the structure, at the origin of additional internal cross-links analogous which rigidify the structure compared to non-functionalized microgels, as proved by their slow adsorption kinetics and poor interfacial compressibility. Upon boronate ester formation with diol groups of the saccharide, the hydrophobic character of the phenylboronic acid decreases, increasing the adsorption kinetics and their interfacial compressibility. Emulsions are stable in the presence of saccharide, given the high deformability of the yet-hydrophilic microgels, and mechanically unstable with less deformable particles in low saccharide concentration. The hydrophobic-hydrophilic switch acts as a trigger to tune the microgel stabilizing properties.
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Affiliation(s)
- Marie-Charlotte Tatry
- Univ. Bordeaux, CNRS, Bordeaux INP, ISM, UMR 5255, F-33400 Talence, France; Centre de Recherche Paul Pascal, UMR 5031, Université de Bordeaux, CNRS, 115 Avenue du Dr A. Schweitzer, 33600 Pessac, France
| | - Yating Qiu
- Univ. Bordeaux, CNRS, Bordeaux INP, ISM, UMR 5255, F-33400 Talence, France
| | - Véronique Lapeyre
- Univ. Bordeaux, CNRS, Bordeaux INP, ISM, UMR 5255, F-33400 Talence, France
| | - Patrick Garrigue
- Univ. Bordeaux, CNRS, Bordeaux INP, ISM, UMR 5255, F-33400 Talence, France
| | - Véronique Schmitt
- Centre de Recherche Paul Pascal, UMR 5031, Université de Bordeaux, CNRS, 115 Avenue du Dr A. Schweitzer, 33600 Pessac, France.
| | - Valérie Ravaine
- Univ. Bordeaux, CNRS, Bordeaux INP, ISM, UMR 5255, F-33400 Talence, France.
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33
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Gavrilov AA, Richtering W, Potemkin II. Polyelectrolyte Microgels at a Liquid–Liquid Interface: Swelling and Long-Range Ordering. J Phys Chem B 2019; 123:8590-8598. [DOI: 10.1021/acs.jpcb.9b07725] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Alexey A. Gavrilov
- Physics Department, Lomonosov Moscow State University, Moscow 119991, Russian Federation
| | - Walter Richtering
- Institute of Physical Chemistry, RWTH Aachen University, Aachen 52056, Germany
| | - Igor I. Potemkin
- Physics Department, Lomonosov Moscow State University, Moscow 119991, Russian Federation
- DWI - Leibniz Institute for Interactive Materials, Aachen 52056, Germany
- National Research South Ural State University, Chelyabinsk 454080, Russian Federation
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34
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Rudyak VY, Kozhunova EY, Chertovich AV. Towards the realistic computer model of precipitation polymerization microgels. Sci Rep 2019; 9:13052. [PMID: 31506571 PMCID: PMC6737091 DOI: 10.1038/s41598-019-49512-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 08/06/2019] [Indexed: 11/08/2022] Open
Abstract
In this paper we propose a new method of coarse-grained computer simulations of the microgel formation in course of free radical precipitation polymerization. For the first time, we simulate the precipitation polymerization process from a dilute solution of initial components to a final microgel particle with coarse grained molecular dynamics, and compare it to the experimental data. We expect that our simulation studies of PNIPA-like microgels will be able to elucidate the subject of nucleation and growth kinetics and to describe in detail the network topology and structure. Performed computer simulations help to determine the characteristic phases of the growth process and show the necessity of prolongated synthesis for the formation of stable microgel particles. We demonstrate the important role of dangling ends in microgels, which occupy as much as 50% of its molecular mass and have previously unattended influence on the swelling behavior. The verification of the model is made by the comparison of collapse curves and structure factors between simulated and experimental systems, and high quality matching is achieved. This work could help to open new horizons in studies that require the knowledge of detailed and realistic structures of the microgel networks.
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Affiliation(s)
- Vladimir Yu Rudyak
- Lomonosov Moscow State University, Faculty of Physics, Moscow, 119991, Russia.
| | - Elena Yu Kozhunova
- Lomonosov Moscow State University, Faculty of Physics, Moscow, 119991, Russia
| | - Alexander V Chertovich
- Lomonosov Moscow State University, Faculty of Physics, Moscow, 119991, Russia
- Semenov Institute of Chemical Physics, Moscow, 119991, Russia
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35
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Murray BS. Microgels at fluid-fluid interfaces for food and drinks. Adv Colloid Interface Sci 2019; 271:101990. [PMID: 31330395 DOI: 10.1016/j.cis.2019.101990] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 07/09/2019] [Accepted: 07/11/2019] [Indexed: 12/11/2022]
Abstract
Various aspects of microgel adsorption at fluid-fluid interfaces of relevance to emulsion and foam stabilization have been reviewed. The emphasis is on the wider non-food literature, with a view to highlighting how this understanding can be applied to food-based systems. The various different types of microgel, their methods of formation and their fundamental behavioral traits at interfaces are covered. The latter includes aspects of microgel deformation and packing at interfaces, their deformability, size, swelling and de-swelling and how this affects their surface activity and stabilizing properties. Experimental and theoretical methods for measuring and modelling their behaviour are surveyed, including interactions between microgels themselves at interfaces but also other surface active species. It is concluded that challenges still remain in translating all the possibilities synthetic microgels offer to microgels based on food-grade materials only, but Nature's rich tool box of biopolymers and biosurfactants suggests that this field will still open up important new avenues of food microstructure development and control.
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36
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Harrer J, Rey M, Ciarella S, Löwen H, Janssen LMC, Vogel N. Stimuli-Responsive Behavior of PNiPAm Microgels under Interfacial Confinement. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:10512-10521. [PMID: 31304759 DOI: 10.1021/acs.langmuir.9b01208] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The volume phase transition of microgels is one of the most paradigmatic examples of stimuli-responsiveness, enabling a collapse from a highly swollen microgel state into a densely coiled state by an external stimulus. Although well characterized in bulk, it remains unclear how the phase transition is affected by the presence of a confining interface. Here, we demonstrate that the temperature-induced volume phase transition of poly(N-isopropylacrylamide) microgels, conventionally considered an intrinsic molecular property of the polymer, is in fact largely suppressed when the microgel is adsorbed to an air/liquid interface. We further observe a hysteresis in the core morphology and interfacial pressure between heating and cooling cycles. Our results, supported by molecular dynamics simulations, reveal that the dangling polymer chains of microgel particles, spread at the interface under the influence of surface tension, do not undergo any volume phase transition. The balance in free energy responsible for the volume phase transition is fundamentally altered by interfacial confinement. These results imply that important technological properties of such systems, including the temperature-induced destabilization of emulsions, do not occur via a decrease in the interfacial coverage of the microgels.
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Affiliation(s)
- Johannes Harrer
- Institute of Particle Technology , Friedrich-Alexander University Erlangen-Nürnberg , Cauerstrasse 4 , 91058 Erlangen , Germany
| | - Marcel Rey
- Institute of Particle Technology , Friedrich-Alexander University Erlangen-Nürnberg , Cauerstrasse 4 , 91058 Erlangen , Germany
| | - Simone Ciarella
- Theory of Polymers and Soft Matter, Department of Applied Physics , Eindhoven University of Technology , P.O. Box 513, 5600MB Eindhoven , The Netherlands
| | - Hartmut Löwen
- Institut für Theoretische Physik II: Weiche Materie , Heinrich-Heine-Universität , D-40225 Düsseldorf , Germany
| | - Liesbeth M C Janssen
- Theory of Polymers and Soft Matter, Department of Applied Physics , Eindhoven University of Technology , P.O. Box 513, 5600MB Eindhoven , The Netherlands
| | - Nicolas Vogel
- Institute of Particle Technology , Friedrich-Alexander University Erlangen-Nürnberg , Cauerstrasse 4 , 91058 Erlangen , Germany
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37
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Tan KH, Xu W, Stefka S, Demco DE, Kharandiuk T, Ivasiv V, Nebesnyi R, Petrovskii VS, Potemkin II, Pich A. Selenium‐Modified Microgels as Bio‐Inspired Oxidation Catalysts. Angew Chem Int Ed Engl 2019; 58:9791-9796. [DOI: 10.1002/anie.201901161] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 03/17/2019] [Indexed: 01/02/2023]
Affiliation(s)
- Kok H. Tan
- DWI Leibniz Institute for Interactive Materials e.V.RWTH Aachen University Forckenbeckstraße 50 52074 Aachen Germany
| | - Wenjing Xu
- DWI Leibniz Institute for Interactive Materials e.V.RWTH Aachen University Forckenbeckstraße 50 52074 Aachen Germany
| | - Simon Stefka
- DWI Leibniz Institute for Interactive Materials e.V.RWTH Aachen University Forckenbeckstraße 50 52074 Aachen Germany
| | - Dan E. Demco
- DWI Leibniz Institute for Interactive Materials e.V.RWTH Aachen University Forckenbeckstraße 50 52074 Aachen Germany
- Technical University of Cluj-NapocaDepartment of Physics and Chemistry Romania
| | - Tetiana Kharandiuk
- Technology of Organic Products DepartmentLviv Polytechnic National University Ukraine
| | - Volodymyr Ivasiv
- Technology of Organic Products DepartmentLviv Polytechnic National University Ukraine
| | - Roman Nebesnyi
- Technology of Organic Products DepartmentLviv Polytechnic National University Ukraine
| | | | - Igor I. Potemkin
- DWI Leibniz Institute for Interactive Materials e.V.RWTH Aachen University Forckenbeckstraße 50 52074 Aachen Germany
- Physics DepartmentLomonosov Moscow State University Russian Federation
- National Research South Ural State University Chelyabinsk Russian Federation
| | - Andrij Pich
- DWI Leibniz Institute for Interactive Materials e.V.RWTH Aachen University Forckenbeckstraße 50 52074 Aachen Germany
- Aachen Maastricht Institute for Biobased Materials (AMIBM)Maastricht University Urmonderbaan 22 6167 RD Geleen The Netherlands
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38
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Tan KH, Xu W, Stefka S, Demco DE, Kharandiuk T, Ivasiv V, Nebesnyi R, Petrovskii VS, Potemkin II, Pich A. Selenmodifizierte Mikrogele als bioinspirierte Oxidationskatalysatoren. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201901161] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Kok H. Tan
- DWI Leibniz Institute für Interaktive Materialien e.V.RWTH Aachen Forckenbeckstraße 50 52074 Aachen Deutschland
| | - Wenjing Xu
- DWI Leibniz Institute für Interaktive Materialien e.V.RWTH Aachen Forckenbeckstraße 50 52074 Aachen Deutschland
| | - Simon Stefka
- DWI Leibniz Institute für Interaktive Materialien e.V.RWTH Aachen Forckenbeckstraße 50 52074 Aachen Deutschland
| | - Dan E. Demco
- DWI Leibniz Institute für Interaktive Materialien e.V.RWTH Aachen Forckenbeckstraße 50 52074 Aachen Deutschland
- Technical University of Cluj-NapocaDepartment of Physics and Chemistry Rumänien
| | - Tetiana Kharandiuk
- Technology of Organic Products DepartmentLviv Polytechnic National University Ukraine
| | - Volodymyr Ivasiv
- Technology of Organic Products DepartmentLviv Polytechnic National University Ukraine
| | - Roman Nebesnyi
- Technology of Organic Products DepartmentLviv Polytechnic National University Ukraine
| | | | - Igor I. Potemkin
- DWI Leibniz Institute für Interaktive Materialien e.V.RWTH Aachen Forckenbeckstraße 50 52074 Aachen Deutschland
- Physics DepartmentLomonosov Moscow State University Russische Förderation
- National Research South Ural State University Chelyabinsk Russische Förderation
| | - Andrij Pich
- DWI Leibniz Institute für Interaktive Materialien e.V.RWTH Aachen Forckenbeckstraße 50 52074 Aachen Deutschland
- Aachen Maastricht Institute for Biobased Materials (AMIBM)Maastricht University Urmonderbaan 22 6167 RD Geleen Niederlande
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39
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Borówko M, Sokołowski S, Staszewski T. Amphiphilic Dimers at Liquid-Liquid Interfaces: A Density Functional Approach. J Phys Chem B 2019; 123:5962-5972. [PMID: 31204480 DOI: 10.1021/acs.jpcb.9b04501] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
We apply density functional theory to study the structure of dimers at the interface between two partially miscible symmetric liquids. The dimers are built of two tangentially jointed spheres and do not solve the coexisting liquids. The interactions in the system are modeled using Lennard-Jones potentials with different interactions between segments of the dimers and the liquid components. We study how asymmetry of the interactions between dimers and molecules of the liquid, i.e., the degree of dimer amphiphilicity, influences the interfacial structure. Two unexpected phenomena have been found. First, for some systems, the liquid-liquid interface is able to accommodate only a finite amount of dimers. If the amount of added dimers is larger than a threshold value, a part or all of the dimers move to the interior one of the coexisting phase, forming an insoluble sheet inside it, or the initial interface splits into separate parts. The second is a peculiar behavior of the dependence of the interfacial width with an increase of the amount of added dimers. In this case, we observe a discontinuous jump that is connected with reorientation of dimers with respect to the interface.
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Affiliation(s)
- M Borówko
- Department for the Modelling of Physico-Chemical Processes , Maria Curie-Skłodowska University , 20031 Lublin , Poland
| | - S Sokołowski
- Department for the Modelling of Physico-Chemical Processes , Maria Curie-Skłodowska University , 20031 Lublin , Poland
| | - T Staszewski
- Department for the Modelling of Physico-Chemical Processes , Maria Curie-Skłodowska University , 20031 Lublin , Poland
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40
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Gumerov RA, Filippov SA, Richtering W, Pich A, Potemkin II. Amphiphilic microgels adsorbed at oil-water interfaces as mixers of two immiscible liquids. SOFT MATTER 2019; 15:3978-3986. [PMID: 31025694 DOI: 10.1039/c9sm00389d] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Amphiphilic microgels adsorbed at an oil-water interface were studied by means of dissipative particle dynamics (DPD) simulations. The hydrophobic (A) and hydrophilic (B) monomer units in the polymer network are considered to be randomly distributed. Effects of the crosslinking density, interfacial tension between the liquids, their selectivity as solvents towards species A and B, and the degree of incompatibility between the A and B units on the internal microgel structure and distribution of the liquids are considered. The most important predictions are that (i) two immiscible liquids can homogeneously be mixed within the microgels and (ii) the adsorbed microgels contain a high fraction of the liquids (they are swollen at the interface). Simultaneous fulfillment of these two conditions can have a high impact on the design of new and efficient catalytic systems. In particular, such microgels can mix immiscible reactants dissolved in water and oil and trigger chemical reactions in the presence of a catalyst embedded into the microgel.
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Affiliation(s)
- Rustam A Gumerov
- Physics Department, Lomonosov Moscow State University, Moscow 119991, Russian Federation.
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Camerin F, Fernández-Rodríguez MÁ, Rovigatti L, Antonopoulou MN, Gnan N, Ninarello A, Isa L, Zaccarelli E. Microgels Adsorbed at Liquid-Liquid Interfaces: A Joint Numerical and Experimental Study. ACS NANO 2019; 13:4548-4559. [PMID: 30865829 DOI: 10.1021/acsnano.9b00390] [Citation(s) in RCA: 73] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Soft particles display highly versatile properties with respect to hard colloids and even more so at fluid-fluid interfaces. In particular, microgels, consisting of a cross-linked polymer network, are able to deform and flatten upon adsorption at the interface due to the balance between surface tension and internal elasticity. Despite the existence of experimental results, a detailed theoretical understanding of this phenomenon is still lacking due to the absence of appropriate microscopic models. In this work, we propose an advanced modeling of microgels at a flat water/oil interface. The model builds on a realistic description of the internal polymeric architecture and single-particle properties of the microgel and is able to reproduce its experimentally observed shape at the interface. Complementing molecular dynamics simulations with in situ cryo-electron microscopy experiments and atomic force microscopy imaging after Langmuir-Blodgett deposition, we compare the morphology of the microgels for different values of the cross-linking ratios. Our model allows for a systematic microscopic investigation of soft particles at fluid interfaces, which is essential to develop predictive power for the use of microgels in a broad range of applications, including the stabilization of smart emulsions and the versatile patterning of surfaces.
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Affiliation(s)
- Fabrizio Camerin
- CNR Institute for Complex Systems, Uos Sapienza , Piazzale Aldo Moro 2 , 00185 Roma , Italy
- Department of Basic and Applied Sciences for Engineering , Sapienza University of Rome , Via Antonio Scarpa 14 , 00161 Roma , Italy
| | - Miguel Ángel Fernández-Rodríguez
- Laboratory for Interfaces, Soft Matter and Assembly, Department of Materials , ETH Zürich , Vladimir-Prelog-Weg 5 , 8093 Zürich , Switzerland
| | - Lorenzo Rovigatti
- CNR Institute for Complex Systems, Uos Sapienza , Piazzale Aldo Moro 2 , 00185 Roma , Italy
- Department of Physics , Sapienza University of Rome , Piazzale Aldo Moro 2 , 00185 Roma , Italy
| | - Maria-Nefeli Antonopoulou
- Laboratory for Interfaces, Soft Matter and Assembly, Department of Materials , ETH Zürich , Vladimir-Prelog-Weg 5 , 8093 Zürich , Switzerland
| | - Nicoletta Gnan
- CNR Institute for Complex Systems, Uos Sapienza , Piazzale Aldo Moro 2 , 00185 Roma , Italy
- Department of Physics , Sapienza University of Rome , Piazzale Aldo Moro 2 , 00185 Roma , Italy
| | - Andrea Ninarello
- CNR Institute for Complex Systems, Uos Sapienza , Piazzale Aldo Moro 2 , 00185 Roma , Italy
- Department of Physics , Sapienza University of Rome , Piazzale Aldo Moro 2 , 00185 Roma , Italy
| | - Lucio Isa
- Laboratory for Interfaces, Soft Matter and Assembly, Department of Materials , ETH Zürich , Vladimir-Prelog-Weg 5 , 8093 Zürich , Switzerland
| | - Emanuela Zaccarelli
- CNR Institute for Complex Systems, Uos Sapienza , Piazzale Aldo Moro 2 , 00185 Roma , Italy
- Department of Physics , Sapienza University of Rome , Piazzale Aldo Moro 2 , 00185 Roma , Italy
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42
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Abstract
Phagocytes protect the organism by ingesting harmful foreign particles and cells. We use mesoscale computer simulations to design a phagocyte-inspired active microcapsule that is capable of selectively capturing nanoparticles dispersed in solvent. Our fully synthetic microdevice is actuated by a temperature-sensitive microgel enclosed inside a perforated spherical shell. The shell pores are decorated with a copolymer brush that regulates the transport of solutes into the capsule interior. When exposed to an external stimulus, the microgel swells, expanding through the shell pores to make contact with the nanoparticle-rich solution surrounding the capsule. Upon removal of the external stimulus, the gel retracts back into the shell, bringing along with it captured nanoparticles. We probe how periodic application of the stimulus combined with nanoparticle-microgel adhesion enable selectivity and enhance capturing efficiency of our nature-inspired microdevice.
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Affiliation(s)
| | - Alberto Fernandez-Nieves
- Department of Condensed Matter Physics, University of Barcelona, 08028 Barcelona, Spain
- ICREA-Institucio Catalana de Recerca i Estudis Avancats, 08010 Barcelona, Spain
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43
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Kwok MH, Sun G, Ngai T. Microgel Particles at Interfaces: Phenomena, Principles, and Opportunities in Food Sciences. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:4205-4217. [PMID: 30836004 DOI: 10.1021/acs.langmuir.8b04009] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The use of soft microgel particles for stabilizing emulsions has captured increasing attention across a wide range of disciplines in the past decades. Being soft, the nanoparticles, which are spherical in solution, undergo a structure change when adsorbed at the oil-water interface. This morphology change leads to the special dynamic properties of interface layers and packing structures, which then alter the interfacial tension and rheological properties of the interface. In addition, emulsions stabilized by these particles, known as Pickering emulsions, can be triggered by changing a variety of environmental conditions, which is especially desirable in industrial applications such as oil transportation processes and biphasic catalysis, where the emulsions can be stabilized and destabilized on demand. Although many studies of the behavior of soft microgel nanoparticles at interfaces have been reported, there are still many challenges in gaining a full understanding of the structure, dynamics, and effective interactions between microgels at the interface. In this Feature Article, we address some of the most important findings and problems in the field. They include the adsorption kinetics of soft microgel particles, particle conformation at the interface, pH and thermal responsiveness, and the interfacial rheological properties of soft-particle-occupied interfaces. We also discuss some potential benefits of using emulsions stabilized by soft particles for food applications as an alternative to conventional surfactant-based systems. We hope to encourage further investigation of these problems, which would be very beneficial to extending this knowledge to all other related soft matter systems.
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Affiliation(s)
- Man-Hin Kwok
- Department of Chemistry , The Chinese University of Hong Kong , Shatin , NT 00852 , Hong Kong
| | - Guanqing Sun
- School of Chemical and Material Engineering , Jiangnan University , Wuxi 214122 , China
| | - To Ngai
- Department of Chemistry , The Chinese University of Hong Kong , Shatin , NT 00852 , Hong Kong
- School of Chemical and Material Engineering , Jiangnan University , Wuxi 214122 , China
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44
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Rumyantsev AM, Leermakers FAM, Zhulina EB, Potemkin II, Borisov OV. Temperature-Induced Re-Entrant Morphological Transitions in Block-Copolymer Micelles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:2680-2691. [PMID: 30720279 DOI: 10.1021/acs.langmuir.8b03747] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Using a combination of a mean-field theoretical method and the numerical Scheutjens-Fleer self-consistent field approach, we predict that it is possible to have re-entrant morphological transitions in nanostructures of diblock copolymers upon variation in temperature-mediated solubility of the associating blocks. This peculiar effect is explained by the different rates in variation of the density of the collapsed core domains and the corresponding interfacial energy as a function of the temperature. The theoretical findings are supported by existing experimental observations of reversed sequences of the morphological transitions occurring upon temperature variation in solutions of amphiphilic block copolymers.
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Affiliation(s)
- Artem M Rumyantsev
- Institut des Sciences Analytiques et de Physico-Chimie pour l'Environnement et les Matériaux, UMR 5254 CNRS UPPA , Pau 64053 , France
- DWI Leibniz Institute for Interactive Materials , Aachen 52056 , Germany
| | - Frans A M Leermakers
- Physical Chemistry and Soft Matter , Wageningen University and Research , Wageningen 6708 WE , The Netherlands
| | - Ekaterina B Zhulina
- Institute of Macromolecular Compounds , Russian Academy of Sciences , St. Petersburg 199004 , Russia
| | - Igor I Potemkin
- DWI Leibniz Institute for Interactive Materials , Aachen 52056 , Germany
- Faculty of Physics , Lomonosov Moscow State University , Moscow 119991 , Russia
- National Research South Ural State University , Chelyabinsk 454080 , Russian Federation
| | - Oleg V Borisov
- Institut des Sciences Analytiques et de Physico-Chimie pour l'Environnement et les Matériaux, UMR 5254 CNRS UPPA , Pau 64053 , France
- Institute of Macromolecular Compounds , Russian Academy of Sciences , St. Petersburg 199004 , Russia
- Peter the Great St. Petersburg State Polytechnic University , 195251 St. Petersburg , Russia
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45
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Rovigatti L, Gnan N, Tavagnacco L, Moreno AJ, Zaccarelli E. Numerical modelling of non-ionic microgels: an overview. SOFT MATTER 2019; 15:1108-1119. [PMID: 30543246 PMCID: PMC6371763 DOI: 10.1039/c8sm02089b] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Accepted: 11/26/2018] [Indexed: 05/03/2023]
Abstract
Microgels are complex macromolecules. These colloid-sized polymer networks possess internal degrees of freedom and, depending on the polymer(s) they are made of, can acquire a responsiveness to variations of the environment (temperature, pH, salt concentration, etc.). Besides being valuable for many practical applications, microgels are also extremely important to tackle fundamental physics problems. As a result, these last years have seen a rapid development of protocols for the synthesis of microgels, and more and more research has been devoted to the investigation of their bulk properties. However, from a numerical standpoint the picture is more fragmented, as the inherently multi-scale nature of microgels, whose bulk behaviour crucially depends on the microscopic details, cannot be handled at a single level of coarse-graining. Here we present an overview of the methods and models that have been proposed to describe non-ionic microgels at different length-scales, from the atomistic to the single-particle level. We especially focus on monomer-resolved models, as these have the right level of details to capture the most important properties of microgels, responsiveness and softness. We suggest that these microscopic descriptions, if realistic enough, can be employed as starting points to develop the more coarse-grained representations required to investigate the behaviour of bulk suspensions.
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Affiliation(s)
- Lorenzo Rovigatti
- Dipartimento di Fisica
, Sapienza Università di Roma
,
Piazzale A. Moro 2
, 00185 Roma
, Italy
.
- CNR-ISC
, Uos Sapienza
,
Piazzale A. Moro 2
, 00185 Roma
, Italy
.
| | - Nicoletta Gnan
- Dipartimento di Fisica
, Sapienza Università di Roma
,
Piazzale A. Moro 2
, 00185 Roma
, Italy
.
- CNR-ISC
, Uos Sapienza
,
Piazzale A. Moro 2
, 00185 Roma
, Italy
.
| | - Letizia Tavagnacco
- Dipartimento di Fisica
, Sapienza Università di Roma
,
Piazzale A. Moro 2
, 00185 Roma
, Italy
.
- CNR-ISC
, Uos Sapienza
,
Piazzale A. Moro 2
, 00185 Roma
, Italy
.
| | - Angel J. Moreno
- Centro de Física de Materiales (CSIC, UPV/EHU) and Materials Physics Center MPC
,
Paseo Manuel de Lardizabal 5
, 20018 San Sebastián
, Spain
- Donostia International Physics Center
,
Paseo Manuel de Lardizabal 4
, 20018 San Sebastian
, Spain
| | - Emanuela Zaccarelli
- Dipartimento di Fisica
, Sapienza Università di Roma
,
Piazzale A. Moro 2
, 00185 Roma
, Italy
.
- CNR-ISC
, Uos Sapienza
,
Piazzale A. Moro 2
, 00185 Roma
, Italy
.
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46
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Gumerov RA, Potemkin II. Swelling of Planar Polymer Brushes in Solvent Vapors. POLYMER SCIENCE SERIES C 2018. [DOI: 10.1134/s181123821802011x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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47
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Portnov IV, Möller M, Richtering W, Potemkin II. Microgel in a Pore: Intraparticle Segregation or Snail-like Behavior Caused by Collapse and Swelling. Macromolecules 2018. [DOI: 10.1021/acs.macromol.8b01569] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Ivan V. Portnov
- Physics Department, Lomonosov Moscow State University, Moscow 119991, Russian Federation
- DWI − Leibniz Institute for Interactive Materials, Aachen 52056, Germany
| | - Martin Möller
- DWI − Leibniz Institute for Interactive Materials, Aachen 52056, Germany
| | - Walter Richtering
- DWI − Leibniz Institute for Interactive Materials, Aachen 52056, Germany
| | - Igor I. Potemkin
- Physics Department, Lomonosov Moscow State University, Moscow 119991, Russian Federation
- DWI − Leibniz Institute for Interactive Materials, Aachen 52056, Germany
- National Research
South Ural State University, Chelyabinsk 454080, Russian Federation
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48
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Camerin F, Gnan N, Rovigatti L, Zaccarelli E. Modelling realistic microgels in an explicit solvent. Sci Rep 2018; 8:14426. [PMID: 30258102 PMCID: PMC6158278 DOI: 10.1038/s41598-018-32642-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Accepted: 08/29/2018] [Indexed: 11/30/2022] Open
Abstract
Thermoresponsive microgels are polymeric colloidal networks that can change their size in response to a temperature variation. This peculiar feature is driven by the nature of the solvent-polymer interactions, which triggers the so-called volume phase transition from a swollen to a collapsed state above a characteristic temperature. Recently, an advanced modelling protocol to assemble realistic, disordered microgels has been shown to reproduce experimental swelling behavior and form factors. In the original framework, the solvent was taken into account in an implicit way, condensing solvent-polymer interactions in an effective attraction between monomers. To go one step further, in this work we perform simulations of realistic microgels in an explicit solvent. We identify a suitable model which fully captures the main features of the implicit model and further provides information on the solvent uptake by the interior of the microgel network and on its role in the collapse kinetics. These results pave the way for addressing problems where solvent effects are dominant, such as the case of microgels at liquid-liquid interfaces.
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Affiliation(s)
- F Camerin
- CNR-ISC, Uos Sapienza, Piazzale A. Moro, 2, 00185, Roma, Italy.
- Dipartimento di Scienze di Base e Applicate per l'Ingegneria, Sapienza Università di Roma, via A. Scarpa, 14, 00161, Roma, Italy.
| | - N Gnan
- CNR-ISC, Uos Sapienza, Piazzale A. Moro, 2, 00185, Roma, Italy
- Dipartimento di Fisica, Sapienza Università di Roma, Piazzale A. Moro, 2, 00185, Roma, Italy
| | - L Rovigatti
- CNR-ISC, Uos Sapienza, Piazzale A. Moro, 2, 00185, Roma, Italy
- Dipartimento di Fisica, Sapienza Università di Roma, Piazzale A. Moro, 2, 00185, Roma, Italy
| | - E Zaccarelli
- CNR-ISC, Uos Sapienza, Piazzale A. Moro, 2, 00185, Roma, Italy.
- Dipartimento di Fisica, Sapienza Università di Roma, Piazzale A. Moro, 2, 00185, Roma, Italy.
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49
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Gavrilov AA, Potemkin II. Adaptive structure of gels and microgels with sliding cross-links: enhanced softness, stretchability and permeability. SOFT MATTER 2018; 14:5098-5105. [PMID: 29873660 DOI: 10.1039/c8sm00192h] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We propose an experimentally-inspired model of gels and microgels with sliding cross-links, and use this model to study the mechanical and structural properties with molecular dynamics simulations. In the model, the gels and microgels are made of linear polymer chains with threaded rings, which are capable of sliding along the chains, and bulky end-groups keeping the rings threaded (thus mimicking polyrotaxanes); the chains are covalently linked to each other not through the backbones but through the rings. Both gels and microgels are shown to be much softer in the regime of intermediate and large deformations and also much more stretchable than the topologically equivalent chemical counterparts. The physical reason for that is the mobility of the cross-links which leads to the formation of long, longitudinally oriented "subchains" between cross-linked rings upon uniaxial deformation. The microgels are tested for adsorption on a solid flat surface and for interaction with colloidal particles of different sizes. We demonstrate that the sliding microgel is subjected to stronger flattening on the surface than the chemical one. Enforced penetration of solid particles into the sliding microgel without breaking of covalent bonds is predicted even if the size of the particles is comparable to or larger than the mesh size of the chemical microgel and smaller than the size of polyrotaxane. This penetration is accompanied by the disappearance of the cavity: the microgel is characterized by adaptive porosity tunable to the guest-object.
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Affiliation(s)
- Alexey A Gavrilov
- Physics Department, Lomonosov Moscow State University, Moscow 119991, Russian Federation.
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50
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Wu D, Honciuc A. Contrasting Mechanisms of Spontaneous Adsorption at Liquid-Liquid Interfaces of Nanoparticles Constituted of and Grafted with pH-Responsive Polymers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:6170-6182. [PMID: 29730929 DOI: 10.1021/acs.langmuir.8b00877] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Elucidating the mechanisms responsible for spontaneous adsorption of nanoparticles (NPs) at interfaces is important for their application as emulsifiers, bubble stabilizers, or foaming agents. In order to investigate the key factors that control the spontaneous adsorption of NPs at liquid-liquid interfaces, we synthesized seven different types of NPs from pH-responsive polymers poly(2-(diethylamino)ethyl methacrylate) (PDEAEMA) and poly(2-dimethylamino)ethyl methacrylate) (PDMAEMA) via surfactant-free emulsion polymerization or via "grafting from" polystyrene (PS) NPs. The dynamic interfacial tension (IFT) measurements at the toluene-water (Tol-H2O) interface reveal that when PDEAEMA and PDMAEMA are grafted from the surface of PS NPs the solubility of the grafted pH-responsive polymers in toluene is the key factor determining the NPs' interfacial adsorption. Under acidic conditions (pH < 6.0), PDEAEMA and PDMAEMA are protonated and show no solubility in toluene, and as a result, the grafted NPs do not adsorb at the Tol-H2O interface. Oppositely, under basic conditions (pH > 7.0), PDMAEMA dissolves in toluene and therefore the PDMAEMA-grafted NPs can adsorb at the Tol-H2O interface. Interestingly, when NPs are constituted of PDEAEMA, they can adsorb spontaneously at the Tol-H2O interface under acidic conditions (pH < 6.0) but not under basic conditions (pH > 7.0). In this case, the key factor determining the NPs' spontaneous adsorption at the Tol-H2O interface is the degree of softness of the NPs rather than the solubility of PDEAEMA in toluene. Furthermore, we found that the adsorption of NPs constituted of PDEAEMA- (pH 2.0-6.0) and PDMAEMA-grafted PS NPs (pH 7.0-10.0) at the Tol-H2O interface is a combination of diffusion-controlled and energy-barrier-controlled. The opposite trends observed for the interfacial attachment Δ E and activation energies Ea for the "constituted of" and "grafted from" NPs with pH suggest an opposite mechanisms of adsorption at the Tol-H2O interface. Finally, the synthesized NPs prove to be effective emulsifiers, where the phase of the Pickering emulsions can be changed dynamically by pH adjustment.
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Affiliation(s)
- Dalin Wu
- Institute of Chemistry and Biotechnology , Zurich University of Applied Sciences , Einsiedlerstrasse 31 , 8820 Waedenswil , Switzerland
| | - Andrei Honciuc
- Institute of Chemistry and Biotechnology , Zurich University of Applied Sciences , Einsiedlerstrasse 31 , 8820 Waedenswil , Switzerland
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