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Hazra N, Lammertz J, Babenyshev A, Erkes R, Hagemans F, Misra C, Richtering W, Crassous JJ. Charged hollow microgel capsules. SOFT MATTER 2024; 20:4608-4620. [PMID: 38813847 DOI: 10.1039/d4sm00111g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2024]
Abstract
Responsive hollow microgels are a fascinating class of soft model systems at the crossover between polymer capsules and microgels. The presence of the cavity makes them promising materials for encapsulation and controlled release applications but also confers them an additional softness that is reflected by their peculiar behaviour in bulk and at interfaces. Their responsivity to external stimuli, such as temperature, pH, and ionic strength, can be designed from their synthesis conditions and the choice of functional moieties. So far most studies have focused on "small" hollow microgels that were mostly studied with scattering or atomic force microscopy techniques. In our previous study, we have shown that large fluorescent hollow poly(N-isopropylacrylamide) (PNIPAM) microgels could be synthesized using micrometer-sized silica particles as sacrificial templates allowing their investigation in situ via confocal microscopy. In this work, we extend this approach to charged large hollow microgels based on poly(N-isopropylacrylamide-co-itaconic acid) (P(NIPAM-co-IA)). Hereby, we compare the structure and responsivity of "neutral" (PNIPAM) and "charged" (P(NIPAM-co-IA)) hollow microgel systems synthesized under similar conditions with the same sacrificial template using confocal and atomic force microscopy and light scattering techniques. In particular, we could demonstrate the extremely soft character of the swollen charged hollow microgels and their responsivity to pH, ionic strength, and temperature. To conclude this study, the buckling behavior of the different capsules was investigated illustrating the potential of such systems to change its conformation by varying the osmotic pressure and pH conditions.
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Affiliation(s)
- Nabanita Hazra
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52074, Aachen, Germany.
| | - Janik Lammertz
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52074, Aachen, Germany.
| | - Andrey Babenyshev
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52074, Aachen, Germany.
| | - Rebecca Erkes
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52074, Aachen, Germany.
| | - Fabian Hagemans
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52074, Aachen, Germany.
| | - Chandeshwar Misra
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52074, Aachen, Germany.
| | - Walter Richtering
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52074, Aachen, Germany.
| | - Jérôme J Crassous
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52074, Aachen, Germany.
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2
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Hildebrandt M, Pham Thuy D, Kippenberger J, Wigger TL, Houston JE, Scotti A, Karg M. Fluid-solid transitions in photonic crystals of soft, thermoresponsive microgels. SOFT MATTER 2023; 19:7122-7135. [PMID: 37695048 DOI: 10.1039/d3sm01062g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
Microgels are often discussed as well-suited model system for soft colloids. In contrast to rigid spheres, the microgel volume and, coupled to this, the volume fraction in dispersion can be manipulated by external stimuli. This behavior is particularly interesting at high packings where phase transitions can be induced by external triggers such as temperature in the case of thermoresponsive microgels. A challenge, however, is the determination of the real volume occupied by these deformable, soft objects and consequently, to determine the boundaries of the phase transitions. Here we propose core-shell microgels with a rigid silica core and a crosslinked, thermoresponsive poly-N-isopropylacrylamide (PNIPAM) shell with a carefully chosen shell-to-core size ratio as ideal model colloids to study fluid-solid transitions that are inducible by millikelvin changes in temperature. Specifically, we identify the temperature ranges where crystallization and melting occur using absorbance spectroscopy in a range of concentrations. Slow annealing from the fluid to the crystalline state leads to photonic crystals with Bragg peaks in the visible wavelength range and very narrow linewidths. Small-angle X-ray scattering is then used to confirm the structure of the fluid phase as well as the long-range order, crystal structure and microgel volume fraction in the solid phase. Thanks to the scattering contrasts and volume ratio of the cores with respect to the shells, the scattering data do allow for form factor analysis revealing osmotic deswelling at volume fractions approaching and also exceeding the hard sphere packing limit.
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Affiliation(s)
- M Hildebrandt
- Institut für Physikalische Chemie I: Kolloide und Nanooptik, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, D-40225 Düsseldorf, Germany.
| | - D Pham Thuy
- Institut für Physikalische Chemie I: Kolloide und Nanooptik, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, D-40225 Düsseldorf, Germany.
| | - J Kippenberger
- Institut für Physikalische Chemie I: Kolloide und Nanooptik, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, D-40225 Düsseldorf, Germany.
| | - T L Wigger
- Institut für Physikalische Chemie I: Kolloide und Nanooptik, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, D-40225 Düsseldorf, Germany.
| | - J E Houston
- European Spallation Source ERIC, Box 176, SE-221 00 Lund, Sweden
| | - A Scotti
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany
| | - M Karg
- Institut für Physikalische Chemie I: Kolloide und Nanooptik, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, D-40225 Düsseldorf, Germany.
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3
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Bushuev NV, Gumerov RA, Rudov AA, Potemkin II. Compression and Ordering of Hollow Microgels in Monolayers Formed at Liquid-Liquid Interfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:12420-12429. [PMID: 37611207 DOI: 10.1021/acs.langmuir.3c01648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/25/2023]
Abstract
Monolayers of polymer microgels with a spherical cavity adsorbed at the liquid-liquid interface were studied using mesoscopic computer simulations. One liquid, named water, was always considered as a good solvent, while the microgel solubility in the second liquid, named oil, was varied. The symmetric and asymmetric cases of vanishing and the strong differences in solubility between the network particles and the liquids were considered. The simulations provided us with an insight into the shape and volume changes of the microgels upon compression, making it possible to relate the response of the individual network with the collective order and structure of the monolayer. Similar to regular microgels, the compression of the monolayer of hollow particles led to a decrease in lateral sizes accompanied by shape transformation from a flattened to a nearly spherical shape. However, the presence of a cavity filled with solvent caused some unique differences in the behavior of the system. The adsorption pathway of hollow microgels at the liquid interface predefines: (a) the position of the particles with respect to the interface and (b) the structure of the monolayer. A striking discovery is that in the symmetric case of similar solubility of the microgel in both liquids, it is possible to produce a monolayer in which one part of the network faces the aqueous phase and the other part faces the oil phase. The polymer concentration profiles plotted along the normal to the interface reveal a redistribution of polymeric mass of the microgels relative to the interface, distinguishing between the microgels whose cavities are filled with water and oil, respectively. Moreover, the ratio between the microgels faced in water and oil does not change upon compression and predetermines the response and order of the monolayer.
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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
| | - Andrey A Rudov
- Physics Department, Lomonosov Moscow State University, Leninskie Gory 1-2, Moscow 119991, Russian Federation
| | - Igor I Potemkin
- Physics Department, Lomonosov Moscow State University, Leninskie Gory 1-2, Moscow 119991, Russian Federation
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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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Moncho-Jordá A, Göth N, Dzubiella J. Liquid structure of bistable responsive macromolecules using mean-field density-functional theory. SOFT MATTER 2023; 19:2832-2846. [PMID: 37000605 DOI: 10.1039/d2sm01523d] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Macromolecular crowding typically applies to biomolecular and polymer-based systems in which the individual particles often feature a two-state folded/unfolded or coil-to-globule transition, such as found for proteins and peptides, DNA and RNA, or supramolecular polymers. Here, we employ a mean-field density functional theory (DFT) of a model of soft and bistable responsive colloids (RCs) in which the size of the macromolecule is explicitly resolved as a degree of freedom living in a bimodal 'Landau' energy landscape (exhibiting big and small states), thus directly responding to the crowding environment. Using this RC-DFT we study the effects of self-crowding on the liquid bulk structure and thermodynamics for different energy barriers and softnesses of the bimodal energy landscape, in conditions close to the coil-to-globule transition. We find substantial crowding effects on the internal distributions, a complex polydispersity behavior, and quasi-universal compression curves for increasing (generalized) packing fractions. Moreover, we uncover distinct signatures of bimodal versus unimodal behavior in the particle compression. Finally, the analysis of the pair structure - derived from the test particle route - reveals that the microstructure of the liquid is quite inhomogeneous due to local depletion effects, tuneable by particle softness.
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Affiliation(s)
- Arturo Moncho-Jordá
- Institute Carlos I for Theoretical and Computational Physics, Facultad de Ciencias, Universidad de Granada, Campus Fuentenueva S/N, 18071 Granada, Spain.
- Departamento de Física Aplicada, Universidad de Granada, Campus Fuentenueva S/N, 18071 Granada, Spain
| | - Nils Göth
- Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, Hermann-Herder Straße 3, D-79104 Freiburg, Germany.
| | - Joachim Dzubiella
- Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, Hermann-Herder Straße 3, D-79104 Freiburg, Germany.
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6
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Zholudev SI, Gumerov RA, Larina AA, Potemkin II. Swelling, collapse and ordering of rod-like microgels in solution: Computer simulation studies. J Colloid Interface Sci 2023; 629:270-278. [PMID: 36155922 DOI: 10.1016/j.jcis.2022.09.050] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 09/03/2022] [Accepted: 09/08/2022] [Indexed: 11/23/2022]
Abstract
Polymer microgels have proven to be highly promising macromolecular objects for a wide variety of applications. In particular, the soft particles of an anisotropic (rod-like) shape are of special interest because of their potential use in tissue engineering or materials design. However, a little is known about the physical behavior of such microgels in solution, which inspired us to study them using mesoscopic computer simulations. For single networks, depending on the solvent quality, the dimensional characteristics were obtained for microgels of different molecular weight, crosslinking density and aspect ratio. In particular, the conditions for the rod-to-rod (preserving the nonspherical shape) and rod-to-sphere collapse were found. In addition, the effect of the liquid-crystalline (LC) ordering was demonstrated for the ensemble of rod-like microgels at different swelling ratios, and the influence of microgel aspect ratio on the volume fraction of the LC transition was shown.
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Affiliation(s)
- Stepan I Zholudev
- 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
| | - Alexandra A Larina
- Physics Department, Lomonosov Moscow State University, Leninskie Gory 1-2, Moscow 119991, Russian Federation
| | - Igor I Potemkin
- Physics Department, Lomonosov Moscow State University, Leninskie Gory 1-2, Moscow 119991, Russian Federation; National Research South Ural State University, Chelyabinsk 454080, Russian Federation.
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7
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Nickel AC, Denton AR, Houston JE, Schweins R, Plivelic TS, Richtering W, Scotti A. Beyond simple self-healing: How anisotropic nanogels adapt their shape to their environment. J Chem Phys 2022; 157:194901. [DOI: 10.1063/5.0119527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The response of soft colloids to crowding depends sensitively on the particles’ compressibility. Nanogel suspensions provide model systems that are often studied to better understand the properties of soft materials and complex fluids from the formation of colloidal crystals to the flow of viruses, blood, or platelet cells in the body. Large spherical nanogels, when embedded in a matrix of smaller nanogels, have the unique ability to spontaneously deswell to match their size to that of the nanogel composing the matrix. In contrast to hard colloids, this self-healing mechanism allows for crystal formation without giving rise to point defects or dislocations. Here, we show that anisotropic ellipsoidal nanogels adapt both their size and their shape depending on the nature of the particles composing the matrix in which they are embedded. Using small-angle neutron scattering with contrast variation, we show that ellipsoidal nanogels become spherical when embedded in a matrix of spherical nanogels. In contrast, the anisotropy of the ellipsoid is enhanced when they are embedded in a matrix of anisotropic nanogels. Our experimental data are supported by Monte Carlo simulations that reproduce the trend of decreasing aspect ratio of ellipsoidal nanogels with increasing crowding by a matrix of spherical nanogels.
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Affiliation(s)
- Anne C. Nickel
- Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany
| | - Alan R. Denton
- Department of Physics, North Dakota State University, Fargo, North Dakota 58108-6050, USA
| | | | - Ralf Schweins
- Institut Laue-Langevin ILL DS/LSS, 71 Avenue des Martyrs, F-38000 Grenoble, France
| | - Tomàs S. Plivelic
- MAX IV Laboratory, Lund University, P.O. Box 118, 22100 Lund, Sweden
| | - Walter Richtering
- Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany
| | - Andrea Scotti
- Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany
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8
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Elancheliyan R, Del Monte G, Chauveau E, Sennato S, Zaccarelli E, Truzzolillo D. Role of Charge Content in the Two-Step Deswelling of Poly( N-isopropylacrylamide)-Based Microgels. Macromolecules 2022. [DOI: 10.1021/acs.macromol.2c00995] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Rajam Elancheliyan
- Laboratoire Charles Coulomb, UMR 5221, CNRS−Université de Montpellier, F-34095 Montpellier, France
| | - Giovanni Del Monte
- National Research Council−Institute for Complex Systems (CNR-ISC), Sapienza University of Rome, 00185 Rome, Italy
- Department of Physics, Sapienza University of Rome, 00185 Rome, Italy
| | - Edouard Chauveau
- Laboratoire Charles Coulomb, UMR 5221, CNRS−Université de Montpellier, F-34095 Montpellier, France
| | - Simona Sennato
- National Research Council−Institute for Complex Systems (CNR-ISC), Sapienza University of Rome, 00185 Rome, Italy
- Department of Physics, Sapienza University of Rome, 00185 Rome, Italy
| | - Emanuela Zaccarelli
- National Research Council−Institute for Complex Systems (CNR-ISC), Sapienza University of Rome, 00185 Rome, Italy
- Department of Physics, Sapienza University of Rome, 00185 Rome, Italy
| | - Domenico Truzzolillo
- Laboratoire Charles Coulomb, UMR 5221, CNRS−Université de Montpellier, F-34095 Montpellier, France
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9
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Scotti A, Gasser U, Petrunin AV, Fruhner L, Richtering W, Houston JE. Experimental determination of the bulk moduli of hollow nanogels. SOFT MATTER 2022; 18:5750-5758. [PMID: 35899831 DOI: 10.1039/d2sm00680d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The softness of an object can be quantified by one of the fundamental elastic moduli. The bulk modulus of the particle is most appropriate in the presence of isotropic compressions. Here, we use small-angle neutron scattering with contrast variation to directly access the bulk modulus of polymeric nanocapsules - pNIPAM-based hollow nanogels. We show that the size of the cavity is the most important quantity that determines the softness of hollow nanogels. During initial compression, the polymer collapses into the cavity and leads to a large change in the particle volume, resulting in a very small initial bulk modulus. Once the cavity is partially occupied by the polymer, the hollow nanogels become significantly stiffer since now the highly crosslinked network has to be compressed. Furthermore, we show that the larger the cavity, the softer the nanogel.
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Affiliation(s)
- Andrea Scotti
- Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany.
| | - Urs Gasser
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, 5232 Villigen, Switzerland
| | | | - Lisa Fruhner
- Forschungszentrum Jülich GmbH Jülich Centre for Neutron Science (JCNS-1) and Institute for Biological Information processing (IBI-8), 52425 Jülich, Germany
| | - Walter Richtering
- Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany.
| | - Judith E Houston
- European Spallation Source ERIC, Box 176, SE-221 00 Lund, Sweden
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10
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Scotti A, Schulte MF, Lopez CG, Crassous JJ, Bochenek S, Richtering W. How Softness Matters in Soft Nanogels and Nanogel Assemblies. Chem Rev 2022; 122:11675-11700. [PMID: 35671377 DOI: 10.1021/acs.chemrev.2c00035] [Citation(s) in RCA: 36] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Softness plays a key role in determining the macroscopic properties of colloidal systems, from synthetic nanogels to biological macromolecules, from viruses to star polymers. However, we are missing a way to quantify what the term "softness" means in nanoscience. Having quantitative parameters is fundamental to compare different systems and understand what the consequences of softness on the macroscopic properties are. Here, we propose different quantities that can be measured using scattering methods and microscopy experiments. On the basis of these quantities, we review the recent literature on micro- and nanogels, i.e. cross-linked polymer networks swollen in water, a widely used model system for soft colloids. Applying our criteria, we address the question what makes a nanomaterial soft? We discuss and introduce general criteria to quantify the different definitions of softness for an individual compressible colloid. This is done in terms of the energetic cost associated with the deformation and the capability of the colloid to isotropically deswell. Then, concentrated solutions of soft colloids are considered. New definitions of softness and new parameters, which depend on the particle-to-particle interactions, are introduced in terms of faceting and interpenetration. The influence of the different synthetic routes on the softness of nanogels is discussed. Concentrated solutions of nanogels are considered and we review the recent results in the literature concerning the phase behavior and flow properties of nanogels both in three and two dimensions, in the light of the different parameters we defined. The aim of this review is to look at the results on micro- and nanogels in a more quantitative way that allow us to explain the reported properties in terms of differences in colloidal softness. Furthermore, this review can give researchers dealing with soft colloids quantitative methods to define unambiguously which softness matters in their compound.
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Affiliation(s)
- Andrea Scotti
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany, European Union
| | - M Friederike Schulte
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany, European Union
| | - Carlos G Lopez
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany, European Union
| | - Jérôme J Crassous
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany, European Union
| | - Steffen Bochenek
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany, European Union
| | - Walter Richtering
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany, European Union
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11
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Gumerov RA, Rudyak VY, Gavrilov AA, Chertovich AV, Potemkin II. Effect of network topology and crosslinker reactivity on microgel structure and ordering at liquid-liquid interface. SOFT MATTER 2022; 18:3738-3747. [PMID: 35506715 DOI: 10.1039/d2sm00269h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Polymer microgels synthesized in silico were studied at a liquid-liquid interface via mesoscopic computer simulations and compared to microgels with ideal (diamond-like) structure. The effect of crosslinkers reactivity ratio on the single particle morphology at the interface and monolayer behavior was examined. It was demonstrated that single particles deform into an explicit core-corona morphology when adsorbed at the interface. An increase in the crosslinker reactivity ratio decreased both the deformation ratio and the ratio between the core and corona sizes. Meanwhile, the compression of microgel monolayers revealed the existence of five distinct interparticle contact regimes, which have been observed experimentally in the literature. The crosslinker reactivity ratio appeared to define the compression range in these regimes and the sharpness of the transition between them. In particular, the higher the crosslinker reactivity ratio, the smaller the corona, and in turn, the narrower the range of the intermediate regime comprising both core-core and corona-corona contacts. The obtained results demonstrate that the more realistic model of microgels synthesized via precipitation polymerization allows for a more accurate prediction of the properties of the microgels at a liquid-liquid interface in comparison to the conventional diamond-like lattice model.
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Affiliation(s)
- Rustam A Gumerov
- Physics Department, Lomonosov Moscow State University, Leninskie Gory 1-2, Moscow 119991, Russian Federation.
| | - Vladimir Yu Rudyak
- Physics Department, Lomonosov Moscow State University, Leninskie Gory 1-2, Moscow 119991, Russian Federation.
| | - Alexey A Gavrilov
- Physics Department, Lomonosov Moscow State University, Leninskie Gory 1-2, Moscow 119991, Russian Federation.
| | - Alexander V Chertovich
- Physics Department, Lomonosov Moscow State University, Leninskie Gory 1-2, Moscow 119991, Russian Federation.
- Semenov Federal Research Center for Chemical Physics, 119991 Moscow, Russian Federation
| | - Igor I Potemkin
- Physics Department, Lomonosov Moscow State University, Leninskie Gory 1-2, Moscow 119991, Russian Federation.
- National Research South Ural State University, Chelyabinsk 454080, Russian Federation
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12
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Nickel AC, Rudov AA, Potemkin II, Crassous JJ, Richtering W. Interfacial Assembly of Anisotropic Core-Shell and Hollow Microgels. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:4351-4363. [PMID: 35349289 DOI: 10.1021/acs.langmuir.2c00093] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Microgels, cross-linked polymers with submicrometer size, are ideal soft model systems. While spherical microgels have been studied extensively, anisotropic microgels have hardly been investigated. In this study, we compare the interfacial deformation and assembly of anisotropic core-shell and hollow microgels. The core-shell microgel consists of an elliptical core of hematite covered with a thin silica layer and a thin shell made of poly(N-isopropylacrylamide). The hollow microgels were obtained after a two-step etching procedure of the inorganic core. The behavior of these microgels at the oil-water interface was investigated in a Langmuir-Blodgett trough combined with ex situ atomic force microscopy. First, the influence of the architecture of anisotropic microgels on their spreading at the interface was investigated experimentally and by dissipative particle dynamic simulations. Hereby, the importance of the local shell thickness on the lateral and longitudinal interfacial deformation was highlighted as well as the differences between the core-shell and hollow architectures. The shape of the compression isotherms as well as the dimensions, ordering, and orientation of the microgels at the different compressions were analyzed. Due to their anisotropic shape and stiffness, both anisotropic microgels were found to exhibit significant capillary interactions with a preferential side-to-side assembly leading to stable microgel clusters at low interfacial coverage. Such capillary interactions were found to decrease in the case of the more deformable hollow anisotropic microgels. Consequently, anisotropic hollow microgels were found to distribute more evenly at high surface pressure compared to stiffer core-shell microgels. Our findings emphasize the complex interplay between the colloid design, anisotropy, and softness on the interfacial assembly and the opportunities it therefore offers to create more complex ordered interfaces.
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Affiliation(s)
- Anne C Nickel
- Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany, European Union
| | - Andrey A Rudov
- DWI-Leibniz-Institute for Interactive Materials, 52056 Aachen, Germany, European Union
| | - Igor I Potemkin
- DWI-Leibniz-Institute for Interactive Materials, 52056 Aachen, Germany, European Union
| | - Jérôme J Crassous
- Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany, European Union
| | - Walter Richtering
- Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany, European Union
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13
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Schulte MF, Izak-Nau E, Braun S, Pich A, Richtering W, Göstl R. Microgels react to force: mechanical properties, syntheses, and force-activated functions. Chem Soc Rev 2022; 51:2939-2956. [PMID: 35319064 DOI: 10.1039/d2cs00011c] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Microgels are colloidal polymer networks with high molar mass and properties between rigid particles, flexible macromolecules, and micellar aggregates. Their unique stimuli-responsiveness in conjunction with their colloidal phase behavior render them useful for many applications ranging from engineering to biomedicine. In many scenarios either the microgel's mechanical properties or its interactions with mechanical force play an important role. Here, we firstly explain microgel mechanical properties and how these are measured by atomic force microscopy (AFM), then we equip the reader with the synthetic background to understand how specific architectures and chemical functionalities enable these mechanical properties, and eventually we elucidate how the interaction of force with microgels can lead to the activation of latent functionality. Since the interaction of microgels with force is a multiscale and multidisciplinary subject, we introduce and interconnect the different research areas that contribute to the understanding of this emerging field in this Tutorial Review.
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Affiliation(s)
- M Friederike Schulte
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany.
| | - Emilia Izak-Nau
- DWI - Leibniz Institute for Interactive Materials, Forckenbeckstr. 50, 52056 Aachen, Germany.
| | - Susanne Braun
- DWI - Leibniz Institute for Interactive Materials, Forckenbeckstr. 50, 52056 Aachen, Germany. .,Institute of Technical and Macromolecular Chemistry, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany
| | - Andrij Pich
- DWI - Leibniz Institute for Interactive Materials, Forckenbeckstr. 50, 52056 Aachen, Germany. .,Institute of Technical and Macromolecular Chemistry, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany.,Maastricht University, Aachen Maastricht Institute for Biobased Materials (AMIBM), Brightlands Chemelot Campus, 6167 RD Geleen, The Netherlands
| | - Walter Richtering
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany.
| | - Robert Göstl
- DWI - Leibniz Institute for Interactive Materials, Forckenbeckstr. 50, 52056 Aachen, Germany.
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14
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Alziyadi MO, Denton AR. Osmotic pressure and swelling behavior of ionic microcapsules. J Chem Phys 2021; 155:214904. [PMID: 34879668 DOI: 10.1063/5.0064282] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Ionic microcapsules are hollow shells of hydrogel, typically 10-1000 nm in radius, composed of cross-linked polymer networks that become charged and swollen in a good solvent. The ability of microcapsules to swell/deswell in response to changes in external stimuli (e.g., temperature, pH, and ionic strength) suits them to applications, such as drug delivery, biosensing, and catalysis. The equilibrium swelling behavior of ionic microcapsules is determined by a balance of electrostatic and elastic forces. The electrostatic component of the osmotic pressure of a microcapsule-the difference in the pressure between the inside and outside of the particle-plays a vital role in determining the swelling behavior. Within the spherical cell model, we derive exact expressions for the radial pressure profile and for the electrostatic and gel components of the osmotic pressure of a microcapsule, which we compute via Poisson-Boltzmann theory and molecular dynamics simulation. For the gel component, we use the Flory-Rehner theory of polymer networks. By combining the electrostatic and gel components of the osmotic pressure, we compute the equilibrium size of ionic microcapsules as a function of particle concentration, shell thickness, and valence. We predict concentration-driven deswelling at relatively low concentrations at which steric interactions between particles are weak and demonstrate that this response can be attributed to crowding-induced redistribution of counterions. Our approach may help to guide the design and applications of smart stimuli-responsive colloidal particles.
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Affiliation(s)
- Mohammed O Alziyadi
- Department of Physics, North Dakota State University, Fargo, North Dakota 58108-6050, USA
| | - Alan R Denton
- Department of Physics, North Dakota State University, Fargo, North Dakota 58108-6050, USA
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15
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Sbeih S, Mohanty PS, Yethiraj A, Morrow MR. 2H NMR Study of Polymer Segmental Dynamics at Varying Cross-Linking in Poly( N-isopropylacrylamide) Microgels. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:13664-13675. [PMID: 34767370 DOI: 10.1021/acs.langmuir.1c02269] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
A microscopic understanding of the internal structure and dynamics of poly(N-isopropylacrylamide) (PNIPAM) chains, in microgel colloids, is developed using deuterium NMR (2H NMR) to study deuterated PNIPAM suspensions as functions of temperature and pressure for four cross-linker molar fractions (f). The PNIPAM polymers were labeled with deuterons at the backbone (d3-PNIPAM) or on side chains (d7-PNIPAM). 2H NMR spectra of the d3-PNIPAM suspensions for all cross-linker molar fractions indicated freely moving chains at low temperature and a nearly immobilized fraction above ∼35 °C. Polymer segments in the collapsed phase of the d3-PNIPAM suspension were more mobile than those in the dry powder. This is direct microscopic evidence that the polymer remains significantly hydrated in the collapsed phase, consistent with strong, indirect evidence from recent light scattering and rheology measurements from our laboratory. However, the observation of a small fraction of immobilized segments in the swollen phase for higher cross-linker molar fraction suggests that, particularly for high levels of cross-linking, some polymer is nonhydrated even in the swollen phase. Finally, variable-pressure NMR (up to 90 MPa) showed a slight increase in transition temperature with pressure for lower cross-linker molar fractions and a larger increase in transition temperature with pressure for higher cross-linker molar fractions. This is consistent with a previously reported dependence of collapse transition enthalpy on cross-linker molar fraction.
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Affiliation(s)
- Suhad Sbeih
- Department of Physics and Physical Oceanography, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada A1B 3X7
- School of Basic Sciences and Humanities, German Jordanian University, P.O. Box 35247, Amman 11180, Jordan
| | - Priti S Mohanty
- School of Chemical Technology, Kalinga Institute of Industrial Technology (KIIT), Bhubaneswar 751024, India
| | - Anand Yethiraj
- Department of Physics and Physical Oceanography, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada A1B 3X7
| | - Michael R Morrow
- Department of Physics and Physical Oceanography, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada A1B 3X7
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16
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Two-step deswelling in the Volume Phase Transition of thermoresponsive microgels. Proc Natl Acad Sci U S A 2021; 118:2109560118. [PMID: 34508008 PMCID: PMC8449345 DOI: 10.1073/pnas.2109560118] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/04/2021] [Indexed: 11/18/2022] Open
Abstract
Microgels, colloidal-scale polymer networks, are the prototype soft colloids. When the constituent polymers are thermoresponsive, they undergo a volume phase transition (VPT) from a swollen to a collapsed state at a characteristic temperature, close to ambient one, of great appeal for several applications. To describe this phenomenon, microgels are usually treated as neutral, but here we show that electrostatics needs to be taken into account. In particular, deswelling occurs via a two-step, rather than a homogeneous, particle collapse, mainly driven by peripheral charges located on the microgel corona, for which we also establish a unifying framework encompassing all studied microgels. Our work thus provides a change of perspective to describe these fascinating systems. Thermoresponsive microgels are one of the most investigated types of soft colloids, thanks to their ability to undergo a Volume Phase Transition (VPT) close to ambient temperature. However, this fundamental phenomenon still lacks a detailed microscopic understanding, particularly regarding the presence and the role of charges in the deswelling process. This is particularly important for the widely used poly(N-isopropylacrylamide)–based microgels, where the constituent monomers are neutral but charged groups arise due to the initiator molecules used in the synthesis. Here, we address this point combining experiments with state-of-the-art simulations to show that the microgel collapse does not happen in a homogeneous fashion, but through a two-step mechanism, entirely attributable to electrostatic effects. The signature of this phenomenon is the emergence of a minimum in the ratio between gyration and hydrodynamic radii at the VPT. Thanks to simulations of microgels with different cross-linker concentrations, charge contents, and charge distributions, we provide evidence that peripheral charges arising from the synthesis are responsible for this behavior and we further build a universal master curve able to predict the two-step deswelling. Our results have direct relevance on fundamental soft condensed matter science and on applications where microgels are involved, ranging from materials to biomedical technologies.
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17
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Vialetto J, Camerin F, Grillo F, Ramakrishna SN, Rovigatti L, Zaccarelli E, Isa L. Effect of Internal Architecture on the Assembly of Soft Particles at Fluid Interfaces. ACS NANO 2021; 15:13105-13117. [PMID: 34328717 PMCID: PMC8388124 DOI: 10.1021/acsnano.1c02486] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Monolayers of soft colloidal particles confined at fluid interfaces are at the core of a broad range of technological processes, from the stabilization of responsive foams and emulsions to advanced lithographic techniques. However, establishing a fundamental relation between their internal architecture, which is controlled during synthesis, and their structural and mechanical properties upon interfacial confinement remains an elusive task. To address this open issue, which defines the monolayer's properties, we synthesize core-shell microgels, whose soft core can be chemically degraded in a controlled fashion. This strategy allows us to obtain a series of particles ranging from analogues of standard batch-synthesized microgels to completely hollow ones after total core removal. Combined experimental and numerical results show that our hollow particles have a thin and deformable shell, leading to a temperature-responsive collapse of the internal cavity and a complete flattening after adsorption at a fluid interface. Mechanical characterization shows that a critical degree of core removal is required to obtain soft disk-like particles at an oil-water interface, which present a distinct response to compression. At low packing fractions, the mechanical response of the monolayer is dominated by the outer polymer chains forming a corona surrounding the particles within the interfacial plane, regardless of the presence of a core. By contrast, at high compression, the absence of a core enables the particles to deform in the direction orthogonal to the interface and to be continuously compressed without altering the monolayer structure. These findings show how fine, single-particle architectural control during synthesis can be engineered to determine the interfacial behavior of microgels, enabling one to link particle conformation with the resulting material 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
| | - Fabrizio Camerin
- CNR
Institute for Complex Systems, Uos Sapienza, P.le A. Moro 2, 00185 Roma, Italy
- Department
of Basic and Applied Sciences for Engineering, Sapienza University of Rome, via A. Scarpa 14, 00161 Roma, Italy
| | - Fabio Grillo
- Laboratory
for Soft Materials and Interfaces, Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 5, 8093 Zürich, Switzerland
| | - Shivaprakash N. Ramakrishna
- Laboratory
for Soft Materials and Interfaces, Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 5, 8093 Zürich, Switzerland
| | - Lorenzo Rovigatti
- CNR
Institute for Complex Systems, Uos Sapienza, P.le A. Moro 2, 00185 Roma, Italy
- Department
of Physics, Sapienza University of Rome, P.le A. Moro 2, 00185 Roma, Italy
| | - Emanuela Zaccarelli
- CNR
Institute for Complex Systems, Uos Sapienza, P.le A. Moro 2, 00185 Roma, Italy
- Department
of Physics, Sapienza University of Rome, P.le A. Moro 2, 00185 Roma, Italy
| | - Lucio Isa
- Laboratory
for Soft Materials and Interfaces, Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 5, 8093 Zürich, Switzerland
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18
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Scotti A. Characterization of the volume fraction of soft deformable microgels by means of small-angle neutron scattering with contrast variation. SOFT MATTER 2021; 17:5548-5559. [PMID: 33978056 DOI: 10.1039/d1sm00277e] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The volume occupied by colloids in a suspension - namely the volume fraction - is the thermodynamic variable that determines the phase behavior of these systems. While for hard incompressible spheres this quantity is well defined, for soft compressible colloids such as microgels - polymeric crosslinked networks swollen in a good solvent - the determination of the real volume occupied by these particles in solution is particularly challenging. This fact depends on two aspects: first the surface and, therefore, the volume of the microgels is hard to define properly given their external fuzziness; second, microgels can osmotically deswell, deform or interpenetrate their neighbors, i.e. change their shape and size depending on the solution concentration. Here, the form factors of few hydrogenated microgels embedded in a matrix of deuterated but otherwise identical microgels are measured using small-angle neutron scattering with contrast variation. From the analysis of the scattering data, the variation of the volume of the microgels as a function of concentration is obtained and used to calculate the real microgel volume fraction in solution. Soft neutral microgels are shown to facet already at low concentrations while in contrast, harder microgels maintain their shape and change their volume.
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Affiliation(s)
- Andrea Scotti
- Institute of Physical Chemistry, RWTH Aachen University, 52056, Aachen, Germany.
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19
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Harrer J, Ciarella S, Rey M, Löwen H, Janssen LMC, Vogel N. Collapse-induced phase transitions in binary interfacial microgel monolayers. SOFT MATTER 2021; 17:4504-4516. [PMID: 33949612 DOI: 10.1039/d1sm00318f] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Microgels, consisting of a swollen polymer network, exhibit a more complex self-assembly behavior compared to incompressible colloidal particles, because of their ability to deform at a liquid interface or collapse upon compression. Here, we investigate the collective phase behavior of two-dimensional binary mixtures of microgels confined at the air/water interface. We use stimuli-responsive poly(N-isopropylacrylamide) microgels with different crosslinking densities, and therefore different morphologies at the interface. We find that the minority microgel population introduces lattice defects in the ordered phase of the majority population, which, in contrast to bulk studies, do not heal out by partial deswelling to accommodate in the lattice. We subsequently investigate the interfacial phase behavior of these binary interfacial assemblies under compression. The binary system exhibits three distinct isostructural solid-solid phase transitions, during which the coronae between two small particles collapse first, followed by the collapse between small-large and large-large microgel pairs. A similar hierarchy of phase transitions is found for mixtures of microgels and core-shell particles. Simulations based on augmented potentials qualitatively reproduce the experimentally observed phase transitions. We rationalize the presence of this hierarchy in phase transitions from differences in the interfacial morphology between the species: the larger coronae of softer (and therefore larger) microgels provide a higher resistance to phase transitions compared to the smaller coronae of the more crosslinked microgels and core-shell particles. The control of phase transitions via the molecular architecture further allows the formation of characteristic, flower-like defects by introducing particles with "weaker" coronae that are more prone to collapse with their neighboring particles. Our findings underline the dominating role of the corona for interfacial microgel assemblies, which acts as an energy barrier, shifting the collapse to higher surface pressures.
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Affiliation(s)
- Johannes Harrer
- Institute of Particle Technology, Friedrich-Alexander University Erlangen-Nürnberg, Cauerstrasse 4, 91058 Erlangen, Germany.
| | - Simone Ciarella
- Soft Matter and Biological Physics, Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands.
| | - Marcel Rey
- Institute of Particle Technology, Friedrich-Alexander University Erlangen-Nürnberg, Cauerstrasse 4, 91058 Erlangen, Germany.
| | - Hartmut Löwen
- Institute for Theoretical Physics II: Soft Matter, Heinrich-Heine University Düsseldorf, D-40225 Düsseldorf, Germany
| | - Liesbeth M C Janssen
- Soft Matter and Biological Physics, Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands.
| | - Nicolas Vogel
- Institute of Particle Technology, Friedrich-Alexander University Erlangen-Nürnberg, Cauerstrasse 4, 91058 Erlangen, Germany.
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20
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Scotti A, Denton AR, Brugnoni M, Schweins R, Richtering W. Absence of crystals in the phase behavior of hollow microgels. Phys Rev E 2021; 103:022612. [PMID: 33736081 DOI: 10.1103/physreve.103.022612] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 01/29/2021] [Indexed: 05/20/2023]
Abstract
Solutions of microgels have been widely used as model systems to gain insight into atomic condensed matter and complex fluids. We explore the thermodynamic phase behavior of hollow microgels, which are distinguished from conventional colloids by a central cavity. Small-angle neutron and x-ray scattering are used to probe hollow microgels in crowded environments. These measurements reveal an interplay among deswelling, interpenetration, and faceting and an unusual absence of crystals. Monte Carlo simulations of model systems confirm that, due to the cavity, solutions of hollow microgels more readily form a supercooled liquid than for microgels with a cross-linked core.
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Affiliation(s)
- A Scotti
- Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany
| | - A R Denton
- Department of Physics, North Dakota State University, Fargo, North Dakota 58108-6050 USA
| | - M Brugnoni
- Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany
| | - R Schweins
- Institut Laue-Langevin ILL DS/LSS, 71 Avenue des Martyrs, F-38000 Grenoble, France
| | - W Richtering
- Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany
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21
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Scotti A, Pelaez-Fernandez M, Gasser U, Fernandez-Nieves A. Osmotic pressure of suspensions comprised of charged microgels. Phys Rev E 2021; 103:012609. [PMID: 33601513 DOI: 10.1103/physreve.103.012609] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Accepted: 12/08/2020] [Indexed: 06/12/2023]
Abstract
We determine the osmotic pressure of microgel suspensions using membrane osmometry and dialysis, for microgels with different softnesses. Our measurements reveal that the osmotic pressure of solutions of both ionic and neutral microgels is determined by the free ions that leave the microgel periphery to maximize their entropy and not by the translational degrees of freedom of the microgels themselves. Furthermore, up to a given concentration it is energetically favorable for the microgels to maintain a constant volume without appreciable deswelling. The concentration where deswelling starts weakly depends on the crosslinker concentration, which affects the microgel dimension; we explain this by considering the dependence of the osmotic pressure and the microgel bulk modulus on the particle size.
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Affiliation(s)
- A Scotti
- Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany
| | - M Pelaez-Fernandez
- Department of Condensed Matter Physics, University of Barcelona, 08028 Barcelona, Spain
| | - U Gasser
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, 5232 Villigen, Switzerland
| | - A Fernandez-Nieves
- Department of Condensed Matter Physics, University of Barcelona, 08028 Barcelona, Spain
- ICREA-Institucio Catalana de Recerca i Estudis Avancats, 08010 Barcelona, Spain
- School of Physics, Georgia Institute of Technology, Atlanta, 30332 Georgia, USA
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22
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Brugnoni M, Fink F, Scotti A, Richtering W. Synthesis and structure of temperature-sensitive nanocapsules. Colloid Polym Sci 2020. [DOI: 10.1007/s00396-020-04686-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
AbstractThe transport and systematic release of functional agents at specific areas are key challenges in various application fields. These make the development of micro- and nanocapsules, which allow for uptake, storage, and triggered release, of high interest. Hollow thermoresponsive microgels, cross-linked polymer networks with a solvent-filled cavity in their center, are promising candidates as triggerable nanocapsules, as they can adapt their size and shape to the environment. Their shell permeability can be controlled by temperature, while the cavity can serve as a storage place for guest species. Here, we present the synthesis and structural characterization of temperature-responsive microgels, which are deswollen at room temperature and swell upon moderate cooling, to facilitate potential encapsulation experiments. We present microgels made from poly(N-isopropylacrylamide-co-diacetone acrylamide), p(NIPAM-co-DAAM), possessing a volume phase transition temperature below room temperature. Their colloidal stability in the deswollen state can be enhanced by adding a swollen polymer shell made of poly(N-isopropylacrylamide), pNIPAM, as periphery. The synthesis of hollow double-shell microgels comprising a cavity surrounded by an inner p(NIPAM-co-DAAM) shell and an outer pNIPAM shell is established. The inner network enables the control of the shell permeability: the network is deswollen at room temperature and swells upon moderate cooling. The outer network guarantees for steric stability at room temperature. Light scattering techniques are employed for the characterization of the microgels. Form factor analysis reveals that the cavity of the nanocapsules persists at all swelling states, making it an ideal site for the storage of guest species.
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23
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Oberdisse J, Hellweg T. Recent advances in stimuli-responsive core-shell microgel particles: synthesis, characterisation, and applications. Colloid Polym Sci 2020. [DOI: 10.1007/s00396-020-04629-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
AbstractInspired by the path followed by Matthias Ballauff over the past 20 years, the development of thermosensitive core-shell microgel structures is reviewed. Different chemical structures, from hard nanoparticle cores to double stimuli-responsive microgels have been devised and successfully implemented by many different groups. Some of the rich variety of these systems is presented, as well as some recent progress in structural analysis of such microstructures by small-angle scattering of neutrons or X-rays, including modelling approaches. In the last part, again following early work by the group of Matthias Ballauff, applications with particular emphasis on incorporation of catalytic nanoparticles inside core-shell structures—stabilising the nanoparticles and granting external control over activity—will be discussed, as well as core-shell microgels at interfaces.
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24
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Linkhorst J, Rabe J, Hirschwald LT, Kuehne AJC, Wessling M. Direct Observation of Deformation in Microgel Filtration. Sci Rep 2019; 9:18998. [PMID: 31831846 PMCID: PMC6908707 DOI: 10.1038/s41598-019-55516-w] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 11/06/2019] [Indexed: 01/09/2023] Open
Abstract
Colloidal filtration processes using porous membranes suffer from productivity loss due to colloidal matter retention and continuous build-up by the retained matter. Especially during filtration of soft matter, the deformation of the individual colloids that make up the filter cake may be significant; however, this deformation and its impact remain unresolved so far. Yet, understanding the deformation on the single colloid level as well as on the ensemble level is important to be able to deconvolute filter cake properties from resistance increase of the membrane either by simultaneous internal adsorption or blocking of pores. Here, we report on the compression of a filter cake by filtrating soft microgels in a microfluidic channel in front of a model membrane. To study the single colloid deformation amorphous and crystalline domains were built up in front of the membrane and visualized on-line using confocal fluorescence microscopy while adjusting the degree of permeation, i.e., the transmembrane flux. Results show locally pronounced asymmetric deformation in amorphous domains, while the microgels in colloidal crystals approached regular polyeder shape. Increasing the flux beyond the maximum colloid deformation results in non-isochoric microgel behavior. The presented methodology enables a realistic description of complex colloidal matter deposits during filtration.
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Affiliation(s)
- John Linkhorst
- RWTH Aachen University, Chemical Process Engineering, Aachen, 52074, Germany
| | - Jonas Rabe
- RWTH Aachen University, Chemical Process Engineering, Aachen, 52074, Germany
| | - Lukas T Hirschwald
- RWTH Aachen University, Chemical Process Engineering, Aachen, 52074, Germany
| | - Alexander J C Kuehne
- DWI - Leibniz Institute for Interactive Materials, Aachen, 52074, Germany
- Ulm University, OC3 - Institute of Organic and Macromolecular Chemistry, Ulm, 89081, Germany
| | - Matthias Wessling
- RWTH Aachen University, Chemical Process Engineering, Aachen, 52074, Germany.
- DWI - Leibniz Institute for Interactive Materials, Aachen, 52074, Germany.
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25
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Wypysek SK, Scotti A, Alziyadi MO, Potemkin II, Denton AR, Richtering W. Tailoring the Cavity of Hollow Polyelectrolyte Microgels. Macromol Rapid Commun 2019; 41:e1900422. [DOI: 10.1002/marc.201900422] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 10/12/2019] [Indexed: 01/03/2023]
Affiliation(s)
- Sarah K. Wypysek
- Institute of Physical ChemistryRWTH Aachen University 52056 Aachen Germany
| | - Andrea Scotti
- Institute of Physical ChemistryRWTH Aachen University 52056 Aachen Germany
| | | | - Igor I. Potemkin
- Physics DepartmentLomonosov Moscow State University Moscow 119991 Russian Federation
- DWI Leibniz Institute for Interactive Materials 52056 Aachen Germany
- Laboratory of Functional MaterialsNational Research South Ural State University Chelyabinsk 454080 Russian Federation
| | - Alan R. Denton
- Department of PhysicsNorth Dakota State University Fargo ND 58108‐6050 USA
| | - Walter Richtering
- Institute of Physical ChemistryRWTH Aachen UniversityJARA ‐ Soft Matter Science 52056 Aachen Germany
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26
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Nickel AC, Scotti A, Houston JE, Ito T, Crassous J, Pedersen JS, Richtering W. Anisotropic Hollow Microgels That Can Adapt Their Size, Shape, and Softness. NANO LETTERS 2019; 19:8161-8170. [PMID: 31613114 DOI: 10.1021/acs.nanolett.9b03507] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The development of soft anisotropic building blocks is of great interest for various applications in soft matter. Furthermore, such systems would be important model systems for ordering phenomena in fundamental soft matter science. In this work, we address the challenge of creating hollow and anisotropically shaped thermoresponsive microgels, polymeric networks with a solvent filled cavity in their center that are swollen in a good solvent. Sacrificial elliptical hematite silica particles were utilized as a template for the synthesis of a cross-linked N-isopropylacrylamide (NIPAm) shell. By varying the amount of NIPAm, two anisotropic microgels were synthesized with either a thin or thick microgel shell. We characterized these precursor core-shell and the resulting hollow microgels using a combination of light, X-ray, and neutron scattering. New form factor models, accounting for the cavity, the polymer distribution and the anisotropy, have been developed for fitting the scattering data. With such models, we demonstrated the existence of the cavity and simultaneously the anisotropic character of the microgels. Furthermore, we show that the thickness of the shell has a major influence on the shape and the cavity dimension of the microgel after etching of the sacrificial core. Finally, the effect of temperature is investigated, showing that changes in size, softness, and aspect ratio are triggered by temperature.
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Affiliation(s)
- Anne C Nickel
- Institute of Physical Chemistry , RWTH Aachen University , 52056 Aachen , Germany
| | - Andrea Scotti
- Institute of Physical Chemistry , RWTH Aachen University , 52056 Aachen , Germany
| | - Judith E Houston
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ) , Forschungszentrum Jülich GmbH , Lichtenbergstrasse 1 , 85748 Garching , Germany
- European Spallation Source ERIC , Box 176, SE-221 00 Lund , Sweden
| | - Thiago Ito
- Physical Chemistry, Department of Chemistry , Lund University , SE-221 00 Lund , Sweden
| | - Jérôme Crassous
- Institute of Physical Chemistry , RWTH Aachen University , 52056 Aachen , Germany
| | - Jan Skov Pedersen
- Department of Chemistry and Interdisciplinary Nanoscience Centre (iNANO) , University of Aarhus , Gustav Wieds Vej 14 , DK-8000 Aarhus C , Denmark
| | - Walter Richtering
- Institute of Physical Chemistry , RWTH Aachen University , 52056 Aachen , Germany
- JARA-SOFT , 52056 Aachen , Germany
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27
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Ninarello A, Crassous JJ, Paloli D, Camerin F, Gnan N, Rovigatti L, Schurtenberger P, Zaccarelli E. Modeling Microgels with a Controlled Structure across the Volume Phase Transition. Macromolecules 2019; 52:7584-7592. [PMID: 31656322 PMCID: PMC6812067 DOI: 10.1021/acs.macromol.9b01122] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 08/20/2019] [Indexed: 12/13/2022]
Abstract
![]()
Thermoresponsive microgels are soft
colloids that find widespread
use as model systems for soft matter physics. Their complex internal
architecture, made of a disordered and heterogeneous polymer network,
has been so far a major challenge for computer simulations. In this
work, we put forward a coarse-grained model of microgels whose structural
properties are in quantitative agreement with results obtained with
small-angle X-ray scattering experiments across a wide range of temperatures,
encompassing the volume phase transition. These results bridge the
gap between experiments and simulations of individual microgel particles,
paving the way to theoretically address open questions about their
bulk properties with unprecedented nano- and microscale resolution.
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Affiliation(s)
- Andrea Ninarello
- CNR-ISC Uos Sapienza, Piazzale A. Moro 2, IT-00185 Roma, Italy.,Department of Physics, Sapienza Università di Roma, Piazzale A. Moro 2, IT-00185 Roma, Italy
| | - Jérôme J Crassous
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, DE-52074 Aachen, Germany.,Physical Chemistry, Department of Chemistry, Lund University, Naturvetarvägen 14, SE-22100 Lund, Sweden
| | - Divya Paloli
- Physical Chemistry, Department of Chemistry, Lund University, Naturvetarvägen 14, SE-22100 Lund, Sweden
| | - Fabrizio Camerin
- CNR-ISC Uos Sapienza, Piazzale A. Moro 2, IT-00185 Roma, Italy.,Department of Basic and Applied Sciences for Engineering, Sapienza Università di Roma, via A. Scarpa 14, IT-00161 Roma, Italy
| | - Nicoletta Gnan
- CNR-ISC Uos Sapienza, Piazzale A. Moro 2, IT-00185 Roma, Italy.,Department of Physics, Sapienza Università di Roma, Piazzale A. Moro 2, IT-00185 Roma, Italy
| | - Lorenzo Rovigatti
- Department of Physics, Sapienza Università di Roma, Piazzale A. Moro 2, IT-00185 Roma, Italy.,CNR-ISC Uos Sapienza, Piazzale A. Moro 2, IT-00185 Roma, Italy
| | - Peter Schurtenberger
- Physical Chemistry, Department of Chemistry, Lund University, Naturvetarvägen 14, SE-22100 Lund, Sweden
| | - Emanuela Zaccarelli
- CNR-ISC Uos Sapienza, Piazzale A. Moro 2, IT-00185 Roma, Italy.,Department of Physics, Sapienza Università di Roma, Piazzale A. Moro 2, IT-00185 Roma, Italy
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28
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Kureha T, Minato H, Suzuki D, Urayama K, Shibayama M. Concentration dependence of the dynamics of microgel suspensions investigated by dynamic light scattering. SOFT MATTER 2019; 15:5390-5399. [PMID: 31204747 DOI: 10.1039/c9sm01030k] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The dynamics of colloidal gel particle suspensions, i.e., microgel suspensions, has been investigated by dynamic light scattering (DLS) over a wide concentration range from the (I) dilute (φ < φcp) to the (II) intermediate (φ ≈ φcp) and (III) high concentration regions (φ ≫ φcp), where φ and φcp are the volume fraction of the gel particles in the suspension and the random close packing fraction, φcp ≈ 0.64, respectively. The time-intensity correlation function exhibited a distinct change with increasing φ, i.e., from ergodic behaviour (region I and II) to nonergodic behaviour (region III). A mode transition from translational (region I) to cooperative diffusion (the so-called gel mode) (region II) was also observed due to the soft and deformable nature of the microgels. Different from the dynamics of hard colloidal glass suspensions, the gel mode remained even at φ ≫ φcp. By using the ensemble-averaged time-correlation function, IE, we quantify the relationship between φ and their dynamics, and show that the soft microgels are deswollen in the densely packed state.
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Affiliation(s)
- Takuma Kureha
- Institute for Solid State Physics, The University of Tokyo, Kashiwa 277-8581, Japan.
| | - Haruka Minato
- Graduate School of Textile Science & Technology, Shinshu University, Ueda 386-8567, Japan
| | - Daisuke Suzuki
- Graduate School of Textile Science & Technology, Shinshu University, Ueda 386-8567, Japan and Division of Smart Textile, Institute for Fiber Engineering, Interdisciplinary Cluster for Cutting Edge Research, Shinshu University, Ueda 386-8567, Japan
| | - Kenji Urayama
- Department of Macromolecular Science and Engineering, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585, Japan
| | - Mitsuhiro Shibayama
- Institute for Solid State Physics, The University of Tokyo, Kashiwa 277-8581, Japan.
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29
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Rovigatti L, Gnan N, Ninarello A, Zaccarelli E. Connecting Elasticity and Effective Interactions of Neutral Microgels: The Validity of the Hertzian Model. Macromolecules 2019. [DOI: 10.1021/acs.macromol.9b00099] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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
| | - Andrea Ninarello
- 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
| | - 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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30
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Honda K, Sazuka Y, Iizuka K, Matsui S, Uchihashi T, Kureha T, Shibayama M, Watanabe T, Suzuki D. Hydrogel Microellipsoids that Form Robust String-Like Assemblies at the Air/Water Interface. Angew Chem Int Ed Engl 2019; 58:7294-7298. [PMID: 30957363 DOI: 10.1002/anie.201901611] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Revised: 03/17/2019] [Indexed: 11/09/2022]
Abstract
Soft colloidal particles such as hydrogel microspheres assemble at air/water or oil/water interfaces, where the soft colloids are highly deformed and their surface polymer chains are highly entangled with each other. Herein, we report the formation of robust one-dimensional, string-like colloidal assemblies through self-organization of hydrogel microspheres with shape anisotropy at the air/water interface of sessile droplets. Shape-anisotropic hydrogel microspheres were synthesized via two-step polymerization, whereby a hydrogel shell was formed onto preformed rigid microellipsoids. The shape anisotropy of the hydrogel microspheres was confirmed by transmission electron microscopy and high-speed atomic force microscopy as well as by light-scattering measurements. The present findings are crucial for the understanding of natural self-organization phenomena, where "softness" influences microscopic assembled structures such as those of Nostoc bacteria.
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Affiliation(s)
- Kenshiro Honda
- Graduate School of Textile Science & Technology, Shinshu University, 3-15-1 Tokida Ueda, Nagano, 386-8567, Japan
| | - Yuka Sazuka
- Graduate School of Textile Science & Technology, Shinshu University, 3-15-1 Tokida Ueda, Nagano, 386-8567, Japan
| | - Kojiro Iizuka
- College of Systems Engineering and Science, Shibaura Institute of Technology, 307 Fukasaku, Minuma-ku, Saitama city, Saitama, 337-8570, Japan
| | - Shusuke Matsui
- Graduate School of Textile Science & Technology, Shinshu University, 3-15-1 Tokida Ueda, Nagano, 386-8567, Japan
| | - Takayuki Uchihashi
- Department of Physics and Structural Biology Research Center, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8602, Japan.,Exploratory Research Center on Life and Living Systems, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi, 444-8787, Japan
| | - Takuma Kureha
- Institute for Solid State Physics, The University of Tokyo, Kashiwanoha, Kashiwa, 277-8581, Japan
| | - Mitsuhiro Shibayama
- Institute for Solid State Physics, The University of Tokyo, Kashiwanoha, Kashiwa, 277-8581, Japan
| | - Takumi Watanabe
- Graduate School of Textile Science & Technology, Shinshu University, 3-15-1 Tokida Ueda, Nagano, 386-8567, Japan
| | - Daisuke Suzuki
- Graduate School of Textile Science & Technology, Shinshu University, 3-15-1 Tokida Ueda, Nagano, 386-8567, Japan.,Division of Smart Textiles, Institute for Fiber Engineering, Interdisciplinary Cluster for Cutting Edge Research, Shinshu University, 3-15-1 Tokida Ueda, Nagano, 386-8567, Japan
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31
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Scotti A, Denton AR, Brugnoni M, Houston JE, Schweins R, Potemkin II, Richtering W. Deswelling of Microgels in Crowded Suspensions Depends on Cross-Link Density and Architecture. Macromolecules 2019. [DOI: 10.1021/acs.macromol.9b00729] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Andrea Scotti
- Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany
| | - Alan R. Denton
- Department of Physics, North Dakota State University, Fargo, North Dakota 58108-6050 United States
| | - Monia Brugnoni
- Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany
| | - Judith E. Houston
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich GmbH, Lichtenbergstr. 1, 85748 Garching, Germany
- European Spallation
Source ERIC, Box 176, SE-221 00 Lund, Sweden
| | - Ralf Schweins
- Institut Laue-Langevin
ILL DS/LSS, 71 Avenue des Martyrs, F-38000 Grenoble, France
| | - Igor I. Potemkin
- Physics Department, Lomonosov Moscow State University, 119991 Moscow, Russian Federation
- DWI - Leibniz
Institute
for Interactive Materials, Aachen 52056, Germany
- National Research South
Ural State University, Chelyabinsk 454080, Russian Federation
| | - Walter Richtering
- Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany
- JARA, Jülich Aachen
Research Alliance, 52056 Aachen, Germany
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32
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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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33
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Karg M, Pich A, Hellweg T, Hoare T, Lyon LA, Crassous JJ, Suzuki D, Gumerov RA, Schneider S, Potemkin II, Richtering W. Nanogels and Microgels: From Model Colloids to Applications, Recent Developments, and Future Trends. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:6231-6255. [PMID: 30998365 DOI: 10.1021/acs.langmuir.8b04304] [Citation(s) in RCA: 310] [Impact Index Per Article: 62.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Nanogels and microgels are soft, deformable, and penetrable objects with an internal gel-like structure that is swollen by the dispersing solvent. Their softness and the potential to respond to external stimuli like temperature, pressure, pH, ionic strength, and different analytes make them interesting as soft model systems in fundamental research as well as for a broad range of applications, in particular in the field of biological applications. Recent tremendous developments in their synthesis open access to systems with complex architectures and compositions allowing for tailoring microgels with specific properties. At the same time state-of-the-art theoretical and simulation approaches offer deeper understanding of the behavior and structure of nano- and microgels under external influences and confinement at interfaces or at high volume fractions. Developments in the experimental analysis of nano- and microgels have become particularly important for structural investigations covering a broad range of length scales relevant to the internal structure, the overall size and shape, and interparticle interactions in concentrated samples. Here we provide an overview of the state-of-the-art, recent developments as well as emerging trends in the field of nano- and microgels. The following aspects build the focus of our discussion: tailoring (multi)functionality through synthesis; the role in biological and biomedical applications; the structure and properties as a model system, e.g., for densely packed arrangements in bulk and at interfaces; as well as the theory and computer simulation.
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Affiliation(s)
- Matthias Karg
- Physical Chemistry I , Heinrich-Heine-University Duesseldorf , 40204 Duesseldorf , Germany
| | - Andrij Pich
- DWI-Leibnitz-Institute for Interactive Materials e.V. , 52056 Aachen , Germany
- Functional and Interactive Polymers, Institute for Technical and Macromolecular Chemistry , RWTH Aachen University , 52056 Aachen , Germany
| | - Thomas Hellweg
- Physical and Biophysical Chemistry , Bielefeld University , 33615 Bielefeld , Germany
| | - Todd Hoare
- Department of Chemical Engineering , McMaster University , Hamilton , Ontario L8S 4L8 , Canada
| | - L Andrew Lyon
- Schmid College of Science and Technology , Chapman University , Orange , California 92866 , United States
| | - J J Crassous
- Institute of Physical Chemistry , RWTH Aachen University , 52056 Aachen , Germany
| | | | - Rustam A Gumerov
- DWI-Leibnitz-Institute for Interactive Materials e.V. , 52056 Aachen , Germany
- Physics Department , Lomonosov Moscow State University , Moscow 119991 , Russian Federation
| | - Stefanie Schneider
- Institute of Physical Chemistry , RWTH Aachen University , 52056 Aachen , Germany
| | - Igor I Potemkin
- DWI-Leibnitz-Institute for Interactive Materials e.V. , 52056 Aachen , Germany
- Physics Department , Lomonosov Moscow State University , Moscow 119991 , Russian Federation
- National Research South Ural State University , Chelyabinsk 454080 , Russian Federation
| | - Walter Richtering
- Institute of Physical Chemistry , RWTH Aachen University , 52056 Aachen , Germany
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34
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Honda K, Sazuka Y, Iizuka K, Matsui S, Uchihashi T, Kureha T, Shibayama M, Watanabe T, Suzuki D. Hydrogel Microellipsoids that Form Robust String‐Like Assemblies at the Air/Water Interface. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201901611] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Kenshiro Honda
- Graduate School of Textile Science & TechnologyShinshu University 3-15-1 Tokida Ueda Nagano 386-8567 Japan
| | - Yuka Sazuka
- Graduate School of Textile Science & TechnologyShinshu University 3-15-1 Tokida Ueda Nagano 386-8567 Japan
| | - Kojiro Iizuka
- College of Systems Engineering and ScienceShibaura Institute of Technology 307 Fukasaku, Minuma-ku Saitama city Saitama 337-8570 Japan
| | - Shusuke Matsui
- Graduate School of Textile Science & TechnologyShinshu University 3-15-1 Tokida Ueda Nagano 386-8567 Japan
| | - Takayuki Uchihashi
- Department of Physics and Structural Biology Research CenterGraduate School of ScienceNagoya University Furo-cho, Chikusa-ku Nagoya Aichi 464-8602 Japan
- Exploratory Research Center on Life and Living SystemsNational Institutes of Natural Sciences 5-1 Higashiyama, Myodaiji Okazaki Aichi 444-8787 Japan
| | - Takuma Kureha
- Institute for Solid State PhysicsThe University of Tokyo Kashiwanoha Kashiwa 277-8581 Japan
| | - Mitsuhiro Shibayama
- Institute for Solid State PhysicsThe University of Tokyo Kashiwanoha Kashiwa 277-8581 Japan
| | - Takumi Watanabe
- Graduate School of Textile Science & TechnologyShinshu University 3-15-1 Tokida Ueda Nagano 386-8567 Japan
| | - Daisuke Suzuki
- Graduate School of Textile Science & TechnologyShinshu University 3-15-1 Tokida Ueda Nagano 386-8567 Japan
- Division of Smart TextilesInstitute for Fiber EngineeringInterdisciplinary Cluster for Cutting Edge ResearchShinshu University 3-15-1 Tokida Ueda Nagano 386-8567 Japan
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35
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Deuteration-Induced Volume Phase Transition Temperature Shift of PNIPMAM Microgels. Polymers (Basel) 2019; 11:polym11040620. [PMID: 30960604 PMCID: PMC6523740 DOI: 10.3390/polym11040620] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 03/25/2019] [Accepted: 03/27/2019] [Indexed: 12/03/2022] Open
Abstract
The effect of deuteration on the volume phase transition (VPT) temperature of poly (N-isopropylmethacrylamide) (pNIPMAM) microgels in aqueous suspension is determined via IR spectroscopy and size measurements by photon correlation spectroscopy (PCS). We study the effect of a hydrogenated and a deuterated solvent (H2O/D2O), and of the hydrogenated and (partially) deuterated monomer. Deuteration of the monomer or copolymerization with deuterated monomers shifts the volume phase transition temperature (VPTT) by up to 8.4 K to higher temperatures, in good agreement with known results for pNIPAM microgels. Moreover, the shape of the swelling curve is found to depend on deuteration, with the highest deuteration leading to the sharpest VPT. Finally, the quantitative agreement between FTIR spectroscopy and PCS evidences the spatial homogeneity of the microgel particles. Our results are rationalized in terms of the effect of deuteration on hydrogen bonding. They shall be of primary importance for any experimental measurements close to the VPT involving isotopic substitution, and in particular contrast variation small angle neutron scattering.
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36
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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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37
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Brugnoni M, Nickel AC, Kröger LC, Scotti A, Pich A, Leonhard K, Richtering W. Synthesis and structure of deuterated ultra-low cross-linked poly(N-isopropylacrylamide) microgels. Polym Chem 2019. [DOI: 10.1039/c8py01699b] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Partial deuteration of the N-isopropylacrylamide monomer reveals new insights into the self-cross-linking of polymer chains in ultra-low cross-linked microgels.
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Affiliation(s)
- Monia Brugnoni
- Institute of Physical Chemistry
- RWTH Aachen University
- 52056 Aachen
- Germany
| | - Anne C. Nickel
- Institute of Physical Chemistry
- RWTH Aachen University
- 52056 Aachen
- Germany
| | - Leif C. Kröger
- Chair of Technical Thermodynamics
- RWTH Aachen University
- 52062 Aachen
- Germany
| | - Andrea Scotti
- Institute of Physical Chemistry
- RWTH Aachen University
- 52056 Aachen
- Germany
| | - Andrij Pich
- Functional and Interactive Polymers
- Institute of Technical and Macromolecular Chemistry
- RWTH Aachen University
- 52056 Aachen
- Germany
| | - Kai Leonhard
- Chair of Technical Thermodynamics
- RWTH Aachen University
- 52062 Aachen
- Germany
| | - Walter Richtering
- Institute of Physical Chemistry
- RWTH Aachen University
- 52056 Aachen
- Germany
| |
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38
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Cors M, Wiehemeier L, Hertle Y, Feoktystov A, Cousin F, Hellweg T, Oberdisse J. Determination of Internal Density Profiles of Smart Acrylamide-Based Microgels by Small-Angle Neutron Scattering: A Multishell Reverse Monte Carlo Approach. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:15403-15415. [PMID: 30421936 DOI: 10.1021/acs.langmuir.8b03217] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The internal structure of nanometric microgels in water has been studied as a function of temperature, cross-linker content, and level of deuteration. Small-angle neutron scattering from poly( N-isopropylmethacrylamide) (volume phase transition ≈ 44 °C) microgel particles of radius well below 100 nm in D2O has been measured. The intensities have been analyzed with a combination of polymer chain scattering and form-free radial monomer volume fraction profiles defined over spherical shells, taking polydispersity in size of the particles determined by atomic force microscopy into account. A reverse Monte Carlo optimization using a limited number of parameters was developed to obtain smoothly decaying profiles in agreement with the experimentally scattered intensities. The results are compared to the swelling curve of microgel particles in the temperature range from 15 to 55 °C obtained from photon correlation spectroscopy (PCS). In addition to hydrodynamic radii measured by PCS, our analysis provides direct information about the internal water content and gradients, the strongly varying steepness of the density profile at the particle-water interface, the total spatial extension of the particles, and the visibility of chains. The model has also been applied to a variation of the cross-linker content, N, N'-methylenebisacrylamide, from 5 to 15 mol %, providing insight on the impact of chain architecture and cross-linking on water uptake and on the definition of the polymer-water interface. The model can easily be generalized to arbitrary monomer contents and types, in particular mixtures of hydrogenated and deuterated species, paving the way to detailed studies of monomer distributions inside more complex microgels, in particular core-shell particles.
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Affiliation(s)
- Marian Cors
- Department of Physical and Biophysical Chemistry , Bielefeld University , Universitätsstr. 25 , 33615 Bielefeld , Germany
- Laboratoire Charles Coulomb (L2C) , University of Montpellier, CNRS , 34095 Montpellier , France
| | - Lars Wiehemeier
- Department of Physical and Biophysical Chemistry , Bielefeld University , Universitätsstr. 25 , 33615 Bielefeld , Germany
| | - Yvonne Hertle
- Department of Physical and Biophysical Chemistry , Bielefeld University , Universitätsstr. 25 , 33615 Bielefeld , Germany
| | - Artem Feoktystov
- Forschungszentrum Jülich GmbH , Jülich Centre for Neutron Science JCNS at Heinz Maier-Leibnitz Zentrum MLZ , 85748 Garching , Germany
| | - Fabrice Cousin
- Laboratoire Léon Brillouin, UMR 12 CEA/CNRS , CEA Saclay, 91191 Gif Sur Yvette , France
| | - Thomas Hellweg
- Department of Physical and Biophysical Chemistry , Bielefeld University , Universitätsstr. 25 , 33615 Bielefeld , Germany
| | - Julian Oberdisse
- Laboratoire Charles Coulomb (L2C) , University of Montpellier, CNRS , 34095 Montpellier , France
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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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