1
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Gupta RR, Daneshi M, Frigaard I, Elfring G. Shear layers and plugs in the capillary flow of wormlike micellar gels. SOFT MATTER 2024; 20:4715-4733. [PMID: 38835212 DOI: 10.1039/d4sm00105b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2024]
Abstract
Wormlike micellar solutions formed by long-chained zwitterionic surfactants show gel-like rheology at room temperature and have recently been found to exhibit other complex and interesting rheological features. We study the dynamics of these wormlike micellar gels in a pipe-flow scenario using particle imaging and tracking velocimetry and report the existence of plug flows with strong wall slip and non-parabolic velocity profiles for different surfactant concentrations and imposed flow rates. We rationalize these results as features of a developing transient flow of a viscoelastic solution in space and time. We show that evolution of shear layers is governed by intermittent flows, asymmetric velocity profiles and flow induced heterogeneity. Our experiments shed light on the transient fluid dynamics of wormlike micelles in simple geometries and highlight the complexity of flows involving wormlike micellar gels and similar soft matter systems in canonical flows.
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Affiliation(s)
- Ronak R Gupta
- Department of Mechanical Engineering, University of British Columbia, 6250 Applied Science Ln, Vancouver, British Columbia V6T1Z4, Canada.
| | - Masoud Daneshi
- Department of Mathematics, University of British Columbia, 1984 Mathematics Road, Vancouver, British Columbia V6T 1Z2, Canada
| | - Ian Frigaard
- Department of Mechanical Engineering, University of British Columbia, 6250 Applied Science Ln, Vancouver, British Columbia V6T1Z4, Canada.
- Department of Mathematics, University of British Columbia, 1984 Mathematics Road, Vancouver, British Columbia V6T 1Z2, Canada
| | - Gwynn Elfring
- Department of Mechanical Engineering, University of British Columbia, 6250 Applied Science Ln, Vancouver, British Columbia V6T1Z4, Canada.
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2
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Höfken T, Gasser U, Schneider S, Petrunin AV, Scotti A. Real and In Silico Microgels Show Comparable Bulk Moduli Below and Above the Volume Phase Transition. Macromol Rapid Commun 2024:e2400043. [PMID: 38613338 DOI: 10.1002/marc.202400043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Revised: 04/02/2024] [Indexed: 04/14/2024]
Abstract
The compressibility of soft colloids influences their phase behavior and flow properties, especially in concentrated suspensions. Particle compressibility, which is proportional to the reciprocal of the bulk modulus K, is a key parameter for soft polymer-based particles that can be compressed in crowded environments. Here, microgels with different degrees of cross-linking, i.e., softness, are investigated below and above their volume phase transition temperature (VPTT). By combining molecular dynamics simulations with small-angle neutron scattering with contrast variation, a change in the particle bulk moduli of two orders of magnitude is observed. The degree of cross-linking has a significant impact on the bulk modulus of the swollen microgel, while above the VPTT the values of K are almost independent of the cross-linking density. The excellent agreement between experimental results and simulations also highlight that the model microgels from computer simulations possess both the internal architecture and the elastic properties of real polymeric networks. This paves the way to a systematic use of simulations to investigate the behavior of dense microgel suspensions below and above their VPTT.
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Affiliation(s)
- Tom Höfken
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52074, Aachen, Germany
| | - Urs Gasser
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, Villigen, 5232, Switzerland
| | - Stefanie Schneider
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52074, Aachen, Germany
| | - Alexander V Petrunin
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52074, Aachen, Germany
| | - Andrea Scotti
- Department of Biomedical Science, Faculty of Health and Society, Malmö University, Malmö, SE-205 06, Sweden
- Biofilms-Research Center for Biointerfaces, Malmö University, Malmö, SE-205 06, Sweden
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3
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Schmidt MM, Ruiz-Franco J, Bochenek S, Camerin F, Zaccarelli E, Scotti A. Interfacial Fluid Rheology of Soft Particles. PHYSICAL REVIEW LETTERS 2023; 131:258202. [PMID: 38181345 DOI: 10.1103/physrevlett.131.258202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 08/18/2023] [Accepted: 11/20/2023] [Indexed: 01/07/2024]
Abstract
In situ interfacial rheology and numerical simulations are used to investigate microgel monolayers in a wide range of packing fractions, ζ_{2D}. The heterogeneous particle compressibility determines two flow regimes characterized by distinct master curves. To mimic the microgel architecture and reproduce experiments, an interaction potential combining a soft shoulder with the Hertzian model is introduced. In contrast to bulk conditions, the elastic moduli vary nonmonotonically with ζ_{2D} at the interface, confirming long-sought predictions of reentrant behavior for Hertzian-like systems.
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Affiliation(s)
- Maximilian M Schmidt
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52074 Aachen, Germany
| | - José Ruiz-Franco
- Laboratory of Physical Chemistry and Soft Matter, Wageningen University & Research, Stippeneng 4, 6708 WE Wageningen, The Netherlands
| | - Steffen Bochenek
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52074 Aachen, Germany
| | - Fabrizio Camerin
- Soft Condensed Matter & Biophysics, Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 1, 3584 CC Utrecht, The Netherlands
| | - Emanuela Zaccarelli
- Italian National Research Council-Institute for Complex Systems (CNR-ISC), Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy
- Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 2, 00185 Rome, Italy
| | - Andrea Scotti
- Department of Biomedical Science, Faculty of Health and Society, Malmö University, SE-205 06 Malmö, Sweden
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4
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Sun M, Ma P, Chen C, Pang Z, Huang Y, Liu X, Wang P. Physiochemical characteristics, morphology, and lubricating properties of size-specific whey protein particles by acid or ion aggregation. Int J Biol Macromol 2023; 252:126346. [PMID: 37586622 DOI: 10.1016/j.ijbiomac.2023.126346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 07/29/2023] [Accepted: 08/13/2023] [Indexed: 08/18/2023]
Abstract
To investigate the influence of particle characteristics on their lubricating capacity, microparticles of controlled size (~300, ~700, and ~1900 nm) were prepared from whey proteins using two different approaches: reducing the pH and increasing the calcium ion concentration. The physiochemical, morphological, and tribological properties of the two types of particles were determined. Both treatments pronouncedly decreased the absolute value of zeta-potential and surface hydrophobicity of whey proteins, with calcium ions showing a more severe effect on zeta-potential. The viscosity of the particle suspensions increased with particle size, and ion-induced samples showed higher viscosity than acid-induced ones. Morphology investigation revealed that particle aggregation and irregularity increased with particle size increase. Distinct lubricating behaviors were observed for the two particle types within different size ranges. Viscosity played a more important role in lubrication when the particle size was small, while particle characteristics became more dominant for large particles.
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Affiliation(s)
- Mengya Sun
- Key Laboratory of Geriatric Nutrition and Health, Beijing Technology and Business University (BTBU), Beijing 100048, China; National Soybean Processing Industry Technology Innovation Center, Beijing Technology & Business University (BTBU), Beijing 100048, China
| | - Peipei Ma
- Key Laboratory of Geriatric Nutrition and Health, Beijing Technology and Business University (BTBU), Beijing 100048, China; National Soybean Processing Industry Technology Innovation Center, Beijing Technology & Business University (BTBU), Beijing 100048, China
| | - Cunshe Chen
- Key Laboratory of Geriatric Nutrition and Health, Beijing Technology and Business University (BTBU), Beijing 100048, China; National Soybean Processing Industry Technology Innovation Center, Beijing Technology & Business University (BTBU), Beijing 100048, China
| | - Zhihua Pang
- Key Laboratory of Geriatric Nutrition and Health, Beijing Technology and Business University (BTBU), Beijing 100048, China; National Soybean Processing Industry Technology Innovation Center, Beijing Technology & Business University (BTBU), Beijing 100048, China.
| | - Yating Huang
- Key Laboratory of Geriatric Nutrition and Health, Beijing Technology and Business University (BTBU), Beijing 100048, China; National Soybean Processing Industry Technology Innovation Center, Beijing Technology & Business University (BTBU), Beijing 100048, China
| | - Xinqi Liu
- Key Laboratory of Geriatric Nutrition and Health, Beijing Technology and Business University (BTBU), Beijing 100048, China; National Soybean Processing Industry Technology Innovation Center, Beijing Technology & Business University (BTBU), Beijing 100048, China.
| | - Pengjie Wang
- Department of Nutrition and Health, China Agricultural University, Beijing 100083, China
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5
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van Westerveld L, Es Sayed J, de Graaf M, Hofman AH, Kamperman M, Parisi D. Hydrophobically modified complex coacervates for designing aqueous pressure-sensitive adhesives. SOFT MATTER 2023; 19:8832-8848. [PMID: 37947361 DOI: 10.1039/d3sm01114c] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2023]
Abstract
The rheology of complex coacervates can be elegantly tuned via the design and control of specific non-covalent hydrophobic interactions between the complexed polymer chains. The well-controlled balance between elasticity and energy dissipation makes complex coacervates perfect candidates for pressure-sensitive adhesives (PSAs). In this work, the polyanion poly(3-sulfopropyl methacrylate) (PSPMA) and the polycation quaternized poly(4-vinylpyridine) (QP4VP) were used to prepare complex coacervates in water. Progressive increase of hydrophobicity is introduced to the polyanion via partial deprotection of the protected precursor. Hence, the polymer chains in the complex coacervates can interact via both electrostatic (controlled by the amount of salt) and hydrophobic (controlled by the deprotection degree) interactions. It was observed that: (i) a rheological time-salt-hydrophobicity superposition principle is applicable, and can be used as a predictive tool for rheology, (ii) the slowdown of the stress relaxation dynamics, due to the increase of hydrophobic stickers (lower deprotection degree), can be captured by the sticky-Rouse model, and (iii) the systematic variation of hydrophobic stickers, amount of salt, and molecular weight of the polymers, enables the identification of optimizing parameters to design aqueous PSA systems. The presented results offer new pathways to control the rheology of complex coacervates and their applicability as PSAs.
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Affiliation(s)
- Larissa van Westerveld
- Zernike Institute for Advanced Materials (ZIAM), University of Groningen, Nijenborgh 4, 9747 AG Groningen, the Netherlands.
| | - Julien Es Sayed
- Zernike Institute for Advanced Materials (ZIAM), University of Groningen, Nijenborgh 4, 9747 AG Groningen, the Netherlands.
| | - Marijn de Graaf
- Zernike Institute for Advanced Materials (ZIAM), University of Groningen, Nijenborgh 4, 9747 AG Groningen, the Netherlands.
| | - Anton H Hofman
- Zernike Institute for Advanced Materials (ZIAM), University of Groningen, Nijenborgh 4, 9747 AG Groningen, the Netherlands.
| | - Marleen Kamperman
- Zernike Institute for Advanced Materials (ZIAM), University of Groningen, Nijenborgh 4, 9747 AG Groningen, the Netherlands.
| | - Daniele Parisi
- Engineering and Technology Institute Groningen (ENTEG), University of Groningen, Nijenborgh 4, 9747 AG Groningen, the Netherlands.
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6
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Thomas JA, Hinton ZR, Korley LTJ. Peptide-polyurea hybrids: a platform for tunable, thermally-stable, and injectable hydrogels. SOFT MATTER 2023; 19:7912-7922. [PMID: 37706333 PMCID: PMC10615840 DOI: 10.1039/d3sm00780d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/15/2023]
Abstract
Drawing inspiration from natural systems, such as the highly segmented structures found in silk fibroin, is an important strategy when designing strong, yet dynamic biomaterials. Polymer-peptide hybrids aim to incorporate the benefits of hierarchical polypeptide structures into synthetic platforms that are promising materials for hydrogel systems due to aspects such as their biocompatibility and structural tunability. In this work, we demonstrated the utility of poly(ethylene glycol) (PEG) peptide-polyurea hybrids as self-assembled hydrogels. Specifically, poly(ε-carbobenzyloxy-L-lysine)-b-PEG-b-poly(ε-carbobenzyloxy-L-lysine) and poly(β-benzyl-L-aspartate)-b-PEG-b-poly(β-benzyl-L-aspartate) triblock copolymers were used as the soft segments in linear peptide-polyurea (PPU) hybrids. We systematically examined the effect of peptide secondary structure and peptide segment length on hydrogelation, microstructure, and rheological properties of our PPU hydrogels. Polymers containing α-helical secondary structures resulted in rapid gelation upon the addition of water, as driven by hierarchical assembly of the peptide segments. Peptide segment length dictated gel strength and resistance to deformation via complex relationships. Simulated injection experiments demonstrated that PPU hydrogels recover their original gel network within 10 s of cessation of high shear. Finally, we showed that PPU hydrogels remain solid-like within the range of 10 to 80 °C; however, a unique softening transition occurs at temperatures corresponding to slight melting of secondary structures. Overall, this bioinspired PPU hybrid platform provides opportunities to design synthetic, bioinspired polymers for hydrogels with tunable microstructure and mechanics for a wide range of thermal and injection-based applications.
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Affiliation(s)
- Jessica A Thomas
- Department of Materials Science and Engineering, University of Delaware, Newark, DE 19716, USA.
| | - Zachary R Hinton
- Department of Materials Science and Engineering, University of Delaware, Newark, DE 19716, USA.
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE 19716, USA
| | - LaShanda T J Korley
- Department of Materials Science and Engineering, University of Delaware, Newark, DE 19716, USA.
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE 19716, USA
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7
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Tian M, Mu X, Fan D, Liu Z, Liu Q, Yue K, Song Z, Luo J, Zhang S. A Transformable Mucoadhesive Microgel Network for Noninvasive Multimodal Imaging And Radioprotection of a Large Area of the Gastrointestinal Tract. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2303436. [PMID: 37364891 DOI: 10.1002/adma.202303436] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 06/04/2023] [Indexed: 06/28/2023]
Abstract
The lack of noninvasive imaging and modulation of a large area of the gastrointestinal (GI) tract constrain the diagnosis and treatment of many GI-related diseases. Recent advances use novel mucoadhesive materials to coat a part of the GI tract and then modulate its functions. High mucoadhesion is the key factor of the partial coating, but also the limitation for not spreading and covering the lower GI tract. Here, a bismuth-pectin organic-inorganic hybrid complex is screened and engineered into a transformable microgel network (Bi-GLUE) with high flowability and mucoadhesion, such that it can quickly transit through and coat a large area of the GI tract. In murine and porcine models, Bi-GLUE delivers contrast agents to achieve real-time, large-area GI-tract imaging under X-ray or magnetic resonance modalities and to facilitate the non-invasive diagnosis of familial adenomatous polyposis. Moreover, Bi-GLUE, like an intracorporal radiation shield, decreases the radiotoxicity in a whole-abdomen irradiation rat model. This transformable microgel network offers a new direction that can modulate a large area of the GI tract and may have broad applications for GI-related conditions.
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Affiliation(s)
- Meng Tian
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, 200030, China
| | - Xin Mu
- Advanced Therapies, Siemens Healthineers Ltd., Shanghai, 200126, China
- School of Biomedical Engineering, ShanghaiTech University, Shanghai, 201210, China
| | - Dongyue Fan
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, 200030, China
- Einthoven Laboratory for Vascular and Regenerative Medicine, Division of Thrombosis and Hemostasis, Department of Internal Medicine, Leiden University Medical Center, Leiden, 2333 ZA, Netherlands
| | - Zhen Liu
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, 200030, China
| | - Qi Liu
- South China Advanced Institute for Soft Matter Science and Technology, School of Emergent Soft Matter, South China University of Technology, Guangzhou, 510640, China
| | - Kan Yue
- South China Advanced Institute for Soft Matter Science and Technology, School of Emergent Soft Matter, South China University of Technology, Guangzhou, 510640, China
| | - Zhiling Song
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, 200030, China
| | - Jie Luo
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, 200030, China
| | - Shiyi Zhang
- School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, 200030, China
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8
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Akgonullu DZ, Murray BS, Connell SD, Fang Y, Linter B, Sarkar A. Synthetic and biopolymeric microgels: Review of similarities and difference in behaviour in bulk phases and at interfaces. Adv Colloid Interface Sci 2023; 320:102983. [PMID: 37690329 DOI: 10.1016/j.cis.2023.102983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 08/12/2023] [Accepted: 08/14/2023] [Indexed: 09/12/2023]
Abstract
This review discusses the current knowledge of interfacial and bulk interactions of biopolymeric microgels in relation to the well-established properties of synthetic microgels for applications as viscosity modifiers and Pickering stabilisers. We present a timeline showing the key milestones in designing microgels and their bulk/ interfacial performance. Poly(N-isopropylacrylamide) (pNIPAM) microgels have remained as the protagonist in the synthetic microgel domain whilst proteins or polysaccharides have been primarily used to fabricate biopolymeric microgels. Bulk properties of microgel dispersions are dominated by the volume fraction (ϕ) of the microgel particles, but ϕ is difficult to pinpoint, as addressed by many theoretical models. By evaluating recent experimental studies over the last five years, we find an increasing focus on the analysis of microgel elasticity as a key parameter in modulating their packing at the interfaces, within the provinces of both synthetic and biopolymeric systems. Production methods and physiochemical factors shown to influence microgel swelling in the aqueous phase can have a significant impact on their bulk as well as interfacial performance. Compared to synthetic microgels, biopolymer microgels show a greater tendency for polydispersity and aggregation and do not appear to have a core-corona structure. Comprehensive studies of biopolymeric microgels are still lacking, for example, to accurately determine their inter- and intra- particle interactions, whilst a wider variety of techniques need to be applied in order to allow comparisons to real systems of practical usage.
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Affiliation(s)
- Daisy Z Akgonullu
- Food Colloids and Bioprocessing Group, School of Food Science and Nutrition, University of Leeds, UK
| | - Brent S Murray
- Food Colloids and Bioprocessing Group, School of Food Science and Nutrition, University of Leeds, UK
| | - Simon D Connell
- Molecular and Nanoscale Physics Group, School of Physics and Astronomy, University of Leeds, UK
| | - Yuan Fang
- PepsiCo, Valhalla, New York, NY, USA
| | | | - Anwesha Sarkar
- Food Colloids and Bioprocessing Group, School of Food Science and Nutrition, University of Leeds, UK.
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9
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Elancheliyan R, Chauveau E, Truzzolillo D. Impact of polyelectrolyte adsorption on the rheology of concentrated poly( N-isopropylacrylamide) microgel suspensions. SOFT MATTER 2023. [PMID: 37318318 DOI: 10.1039/d3sm00317e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
We explore the impact of three water-soluble polyelectrolytes (PEs) on the flow of concentrated suspensions of poly(N-isopropylacrylamide) (PNIPAm) microgels with thermoresponsive anionic charge density. By progressively adding the PEs to a jammed suspension of swollen microgels, we show that the rheology of the mixtures is remarkably influenced by the sign of the PE charge, PE concentration and hydrophobicity only when the temperature is increased above the microgel volume phase transition temperature Tc, namely when microgels collapse, they are partially hydrophobic and form a volume-spanning colloidal gel. We find that the original gel is strengthened close to the isoelectric point, attained when microgels are mixed with cationic PEs, while PE hydrophobicity rules the gel strengthening at very high PE concentrations. Surprisingly, we find that polyelectrolyte adsorption or partial embedding of PE chains inside the microgel periphery occurs also when anionic polymers of polystyrene sulfonate with a high degree of sulfonation are added. This gives rise to colloidal stabilization and to the melting of the original gel network above Tc. Contrastingly, the presence of polyelectrolytes in suspensions of swollen, jammed microgels results in a weak softening of the original repulsive glass, even when an apparent isoelectric condition is met. Our study puts forward the crucial role of electrostatics in thermosensitive microgels, unveiling an exciting new way to tailor the flow of these soft colloids and highlighting a largely unexplored path to engineer soft colloidal mixtures.
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Affiliation(s)
- Rajam Elancheliyan
- Laboratoire Charles Coulomb, UMR 5221, CNRS-Université de Montpellier, F-34095 Montpellier, France.
| | - Edouard Chauveau
- Laboratoire Charles Coulomb, UMR 5221, CNRS-Université de Montpellier, F-34095 Montpellier, France.
| | - Domenico Truzzolillo
- Laboratoire Charles Coulomb, UMR 5221, CNRS-Université de Montpellier, F-34095 Montpellier, France.
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10
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Petrunin AV, Schmidt MM, Schweins R, Houston JE, Scotti A. Self-Healing of Charged Microgels in Neutral and Charged Environments. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023. [PMID: 37220302 DOI: 10.1021/acs.langmuir.2c03054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The softness of microgels depends on many aspects, such as particle characteristic lengths, sample concentration, chemical composition of the sample, and elastic moduli of the particle. Here, the response to crowding of ionic microgels is studied. Charged and uncharged ionic microgels are studied in concentrated suspensions of both neutral and ionic microgels with the same swollen size. The combination of small-angle X-ray and neutron scattering with contrast variation allows us to probe both the particle-to-particle arrangement and the response of individual ionic microgels to crowding. When the ionic microgels are uncharged, initial isotropic deswelling followed by faceting is observed. Therefore, the ionizable groups in the polymeric network do not affect the response of the ionic microgel to crowding, which is similar to what has been reported for neutral microgels. In contrast, the kind of microgels composing the matrix plays a key role once the ionic microgels are charged. If the matrix is composed of neutral microgels, a pronounced faceting and negligible deswelling is observed. When only charged ionic microgels are present in the suspension, isotropic deswelling without faceting is dominant.
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Affiliation(s)
- Alexander V Petrunin
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52074 Aachen, Germany
| | - Maximilian M Schmidt
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52074 Aachen, Germany
| | - Ralf Schweins
- Institut Laue-Langevin ILL, DS/LSS, 71 Avenue des Martyrs, F-38000 Grenoble, France
| | - Judith E Houston
- European Spallation Source ERIC, Box 176, SE-221 00 Lund, Sweden
| | - Andrea Scotti
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52074 Aachen, Germany
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11
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Jansen-van Vuuren RD, Naficy S, Ramezani M, Cunningham M, Jessop P. CO 2-responsive gels. Chem Soc Rev 2023; 52:3470-3542. [PMID: 37128844 DOI: 10.1039/d2cs00053a] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
CO2-responsive materials undergo a change in chemical or physical properties in response to the introduction or removal of CO2. The use of CO2 as a stimulus is advantageous as it is abundant, benign, inexpensive, and it does not accumulate in a system. Many CO2-responsive materials have already been explored including polymers, latexes, surfactants, and catalysts. As a sub-set of CO2-responsive polymers, the study of CO2-responsive gels (insoluble, cross-linked polymers) is a unique discipline due to the unique set of changes in the gels brought about by CO2 such as swelling or a transformed morphology. In the past 15 years, CO2-responsive gels and self-assembled gels have been investigated for a variety of emerging potential applications, reported in 90 peer-reviewed publications. The two most widely exploited properties include the control of flow (fluids) via CO2-triggered aggregation and their capacity for reversible CO2 absorption-desorption, leading to applications in Enhanced Oil Recovery (EOR) and CO2 sequestration, respectively. In this paper, we review the preparation, properties, and applications of these CO2-responsive gels, broadly classified by particle size as nanogels, microgels, aerogels, and macrogels. We have included a section on CO2-induced self-assembled gels (including poly(ionic liquid) gels).
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Affiliation(s)
- Ross D Jansen-van Vuuren
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, 1000 Ljubljana, Slovenia
| | - Sina Naficy
- School of Chemical and Biomolecular Engineering, Centre for Excellence in Advanced Food Enginomics (CAFE), The University of Sydney, Sydney, NSW 2006, Australia
| | - Maedeh Ramezani
- Department of Chemistry, Chernoff Hall, Queen's University, Kingston, Ontario, K7K 2N1, Canada.
| | - Michael Cunningham
- Department of Engineering, Dupuis Hall, Queen's University, Kingston, Ontario, K7L 3N6, Canada
| | - Philip Jessop
- Department of Chemistry, Chernoff Hall, Queen's University, Kingston, Ontario, K7K 2N1, Canada.
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12
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Chen C, van der Naald M, Singh A, Dolinski ND, Jackson GL, Jaeger HM, Rowan SJ, de Pablo JJ. Leveraging the Polymer Glass Transition to Access Thermally Switchable Shear Jamming Suspensions. ACS CENTRAL SCIENCE 2023; 9:639-647. [PMID: 37122459 PMCID: PMC10141574 DOI: 10.1021/acscentsci.2c01338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Indexed: 05/03/2023]
Abstract
Suspensions of polymeric nano- and microparticles are fascinating stress-responsive material systems that, depending on their composition, can display a diverse range of flow properties under shear, such as drastic thinning, thickening, and even jamming (reversible solidification driven by shear). However, investigations to date have almost exclusively focused on nonresponsive particles, which do not allow in situ tuning of the flow properties. Polymeric materials possess rich phase transitions that can be directly tuned by their chemical structures, which has enabled researchers to engineer versatile adaptive materials that can respond to targeted external stimuli. Reported herein are suspensions of (readily prepared) micrometer-sized polymeric particles with accessible glass transition temperatures (T g) designed to thermally control their non-Newtonian rheology. The underlying mechanical stiffness and interparticle friction between particles change dramatically near T g. Capitalizing on these properties, it is shown that, in contrast to conventional systems, a dramatic and nonmonotonic change in shear thickening occurs as the suspensions transition through the particles' T g. This straightforward strategy enables the in situ turning on (or off) of the system's ability to shear jam by varying the temperature relative to T g and lays the groundwork for other types of stimuli-responsive jamming systems through polymer chemistry.
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Affiliation(s)
- Chuqiao Chen
- Pritzker
School of Molecular Engineering, University
of Chicago, Chicago, Illinois 60637, USA
| | | | - Abhinendra Singh
- Pritzker
School of Molecular Engineering, University
of Chicago, Chicago, Illinois 60637, USA
- James
Franck Institute, The University of Chicago, Chicago, Illinois 60637, USA
- Department
of Macromolecular Science and Engineering, Case Western Reserve University, Cleveland, Ohio 44106, USA
| | - Neil D. Dolinski
- Pritzker
School of Molecular Engineering, University
of Chicago, Chicago, Illinois 60637, USA
| | - Grayson L. Jackson
- James
Franck Institute, The University of Chicago, Chicago, Illinois 60637, USA
| | - Heinrich M. Jaeger
- Department
of Physics, The University of Chicago, Chicago, Illinois 60637, USA
- James
Franck Institute, The University of Chicago, Chicago, Illinois 60637, USA
| | - Stuart J. Rowan
- Pritzker
School of Molecular Engineering, University
of Chicago, Chicago, Illinois 60637, USA
- Department
of Chemistry, The University of Chicago, Chicago, Illinois 60637, USA
- Center
for
Molecular Engineering, Argonne National
Laboratory, Lemont, Illinois 60439, USA
- E-mail:
| | - Juan J. de Pablo
- Pritzker
School of Molecular Engineering, University
of Chicago, Chicago, Illinois 60637, USA
- Center
for
Molecular Engineering, Argonne National
Laboratory, Lemont, Illinois 60439, USA
- E-mail:
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13
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Shaulli X, Rivas-Barbosa R, Bergman MJ, Zhang C, Gnan N, Scheffold F, Zaccarelli E. Probing Temperature Responsivity of Microgels and Its Interplay with a Solid Surface by Super-Resolution Microscopy and Numerical Simulations. ACS NANO 2023; 17:2067-2078. [PMID: 36656959 PMCID: PMC9933603 DOI: 10.1021/acsnano.2c07569] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 01/12/2023] [Indexed: 06/17/2023]
Abstract
Super-resolution microscopy has become a powerful tool to investigate the internal structure of complex colloidal and polymeric systems, such as microgels, at the nanometer scale. An interesting feature of this method is the possibility of monitoring microgel response to temperature changes in situ. However, when performing advanced microscopy experiments, interactions between the particle and the environment can be important. Often microgels are deposited on a substrate, since they have to remain still for several minutes during the experiment. This study uses direct stochastic optical reconstruction microscopy (dSTORM) and advanced coarse-grained molecular dynamics simulations to investigate how individual microgels anchored on hydrophilic and hydrophobic surfaces undergo their volume phase transition with temperature. We find that, in the presence of a hydrophilic substrate, the structure of the microgel is unperturbed and the resulting density profiles quantitatively agree with simulations performed under bulk conditions. Instead, when a hydrophobic surface is used, the microgel spreads at the interface and an interesting competition between the two hydrophobic strengths,monomer-monomer vs monomer-surface,comes into play at high temperatures. The robust agreement between experiments and simulations makes the present study a fundamental step to establish this high-resolution monitoring technique as a platform for investigating more complex systems, these being either macromolecules with peculiar internal structure or nanocomplexes where molecules of interest can be encapsulated in the microgel network and controllably released with temperature.
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Affiliation(s)
- Xhorxhina Shaulli
- Department
of Physics, University of Fribourg, Chemin du Musée 3, 1700Fribourg, Switzerland
| | - Rodrigo Rivas-Barbosa
- Department
of Physics, Sapienza University of Rome, Piazzale Aldo Moro 2, 00185Roma, Italy
| | - Maxime J. Bergman
- Department
of Physics, University of Fribourg, Chemin du Musée 3, 1700Fribourg, Switzerland
| | - Chi Zhang
- Department
of Physics, University of Fribourg, Chemin du Musée 3, 1700Fribourg, Switzerland
| | - Nicoletta Gnan
- Department
of Physics, Sapienza University of Rome, Piazzale Aldo Moro 2, 00185Roma, Italy
- CNR
Institute of Complex Systems, Uos Sapienza, Piazzale Aldo Moro 2, 00185Roma, Italy
| | - Frank Scheffold
- Department
of Physics, University of Fribourg, Chemin du Musée 3, 1700Fribourg, Switzerland
| | - Emanuela Zaccarelli
- Department
of Physics, Sapienza University of Rome, Piazzale Aldo Moro 2, 00185Roma, Italy
- CNR
Institute of Complex Systems, Uos Sapienza, Piazzale Aldo Moro 2, 00185Roma, Italy
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14
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Jammed microgels fabricated via various methods for biological studies. KOREAN J CHEM ENG 2023. [DOI: 10.1007/s11814-022-1310-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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15
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Emiroglu DB, Bekcic A, Dranseikiene D, Zhang X, Zambelli T, deMello AJ, Tibbitt MW. Building block properties govern granular hydrogel mechanics through contact deformations. SCIENCE ADVANCES 2022; 8:eadd8570. [PMID: 36525484 PMCID: PMC9757745 DOI: 10.1126/sciadv.add8570] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Accepted: 11/16/2022] [Indexed: 06/17/2023]
Abstract
Granular hydrogels have been increasingly exploited in biomedical applications, including wound healing and cardiac repair. Despite their utility, design guidelines for engineering their macroscale properties remain limited, as we do not understand how the properties of granular hydrogels emerge from collective interactions of their microgel building blocks. In this work, we related building block features (stiffness and size) to the macroscale properties of granular hydrogels using contact mechanics. We investigated the mechanics of the microgel packings through dynamic oscillatory rheology. In addition, we modeled the system as a collection of two-body interactions and applied the Zwanzig and Mountain formula to calculate the plateau modulus and viscosity of the granular hydrogels. The calculations agreed with the dynamic mechanical measurements and described how microgel properties and contact deformations define the rheology of granular hydrogels. These results support a rational design framework for improved engineering of this fascinating class of materials.
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Affiliation(s)
- Dilara Börte Emiroglu
- Macromolecular Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
- Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, 8093 Zurich, Switzerland
| | - Aleksandar Bekcic
- Macromolecular Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
| | - Dalia Dranseikiene
- Macromolecular Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
| | - Xinyu Zhang
- Laboratory of Biosensors and Bioelectronics, Department of Information Technology and Electrical Engineering, ETHZurich, 8093 Zurich, Switzerland
| | - Tomaso Zambelli
- Laboratory of Biosensors and Bioelectronics, Department of Information Technology and Electrical Engineering, ETHZurich, 8093 Zurich, Switzerland
| | - Andrew J. deMello
- Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, 8093 Zurich, Switzerland
| | - Mark W. Tibbitt
- Macromolecular Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
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16
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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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17
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Kumar C, Srivastava S. Structural and Dynamical Studies of a Lipid-Nanoclay Composite Layer at the Air-Water Interface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:10400-10411. [PMID: 35973133 DOI: 10.1021/acs.langmuir.2c00987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
We modulate the adsorption affinities of nanoclay particles for the air-water interface by changing the cationic surface charge composition of the lipid monolayer and thereby tune the attractive electrostatic interaction between the positively charged lipid layer and the zwitterionic nanoclay particles in the water subphase. Our findings emphasize the significance of electrostatic interaction between lipids and the nanoclay, as well as its impact on the structural and viscoelastic features of the composite layer. We use surface pressure (Π)-mean molecular area (A) isotherms, atomic force microscope (AFM), Brewster angle microscopy (BAM), and energy dispersive X-ray spectrsocopy (EDXS) measurements to analyze the structure phases of lipid and lipid-nanoclay composite interfacial layer. The Π-A isotherm curve shows that the lipid-nanoclay composite layer has a larger lift-off area than the neat lipid layer, indicating that nanoparticles adsorb at the lipid layer via electrostatic interaction between lipid and nanoclay molecules. The surface density of the adsorbed nanoclay particles increases with an increase in the composition of the cationic lipid molecules. The stress relaxation response of the composite layer, measured using step compression measurements, exhibits exponential decay and ubiquitous dependence on the cationic dimyristoy-trimethylammonium propane (DMTAP) composition in the lipid layer with crossover to faster relaxation dynamics at DMTAP > 0.75. The power-law study of the frequency-dependent dynamic viscoelastic responses of the interfacial layer, measured using the barrier oscillation method, reveals a transition from glass-like response from neat lipid layer to gel-like dynamic response for the lipid-nanoclay composite layer. A solid-like behavior is evident for all the interface layers with dilation elastic modulus (E') > dilational viscous modulus (E″); however, the dynamic response of the neat layer is largely frequency-independent, whereas lipid-nanoclay composite layers with DMTAP > 0.75 reveal a frequency-dependent dynamic responses. The frequency-dependent power-law exponent of E', E″ increases on increasing the fractional composition of cationic DMTAP from 0.1 to 1.0, which forms a saturated interface of laponite particles and behaves as a viscoelastic gel in 2D.
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Affiliation(s)
- Chandan Kumar
- Soft Matter and Nanomaterials Laboratory, Department of Physics, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Sunita Srivastava
- Soft Matter and Nanomaterials Laboratory, Department of Physics, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
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18
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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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19
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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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20
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Behavior of colloidal gels made of thermoresponsive anisotropic nanoparticles. Sci Rep 2022; 12:12157. [PMID: 35840648 PMCID: PMC9287383 DOI: 10.1038/s41598-022-16414-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Accepted: 07/11/2022] [Indexed: 11/09/2022] Open
Abstract
Amongst colloidal gels, those designed by the assembly of anisotropic colloidal particles tend to form fibrillar gels and are attracting interest as artificial cell growth environments since they have a structure reminiscent of biological extracellular matrices. Their properties can be tuned by controlling the size, shape, and rigidity of the nanoparticles used during their formation. Herein, the relationship between the physical and mechanical properties of the nanocolloidal building blocks and the properties of the resulting gels is investigated. Thermoresponsive particles with different aspect ratios and controlled rigidity were prepared, and the gelation and the properties of the resulting gels were studied. The results show how the aspect ratio and rigidity of polymer colloids tune the properties of the gels. An increase in the aspect ratio of the nanocolloid used led to a sol–gel transition observed at lower particle concentration, but an increase in the rigidity of the nanocolloids delayed the sol–gel transition to higher concentration. However, at a constant concentration, increases in the anisotropy produced gels with higher modulus and lower yield strain. Similarly, an increase in rigidity of the colloids increased the modulus and reduced the yield strain of the resulting gels.
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21
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Houston JE, Fruhner L, de la Cotte A, Rojo González J, Petrunin AV, Gasser U, Schweins R, Allgaier J, Richtering W, Fernandez-Nieves A, Scotti A. Resolving the different bulk moduli within individual soft nanogels using small-angle neutron scattering. SCIENCE ADVANCES 2022; 8:eabn6129. [PMID: 35776796 PMCID: PMC10883365 DOI: 10.1126/sciadv.abn6129] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The bulk modulus, K, quantifies the elastic response of an object to an isotropic compression. For soft compressible colloids, knowing K is essential to accurately predict the suspension response to crowding. Most colloids have complex architectures characterized by different softness, which additionally depends on compression. Here, we determine the different values of K for the various morphological parts of individual nanogels and probe the changes of K with compression. Our method uses a partially deuterated polymer, which exerts the required isotropic stress, and small-angle neutron scattering with contrast matching to determine the form factor of the particles without any scattering contribution from the polymer. We show a clear difference in softness, compressibility, and evolution of K between the shell of the nanogel and the rest of the particle, depending on the amount of cross-linker used in their synthesis.
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Affiliation(s)
| | - Lisa Fruhner
- Forschungszentrum Jülich GmbH Jülich Centre for Neutron Science (JCNS-1) and Institute for Biological Information Processing (IBI-8), 52425 Jülich, Germany
| | - Alexis de la Cotte
- Department of Condensed Matter Physics, University of Barcelona, 08028 Barcelona, Spain
| | - Javier Rojo González
- Department of Condensed Matter Physics, University of Barcelona, 08028 Barcelona, Spain
| | | | - Urs Gasser
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, 5232 Villigen, Switzerland
| | - Ralf Schweins
- Institut Laue-Langevin ILL DS/LSS, 71 Avenue des Martyrs, F-38000 Grenoble, France
| | - Jürgen Allgaier
- 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
- JARA-SOFT, 52056 Aachen, Germany
| | - Alberto Fernandez-Nieves
- Department of Condensed Matter Physics, University of Barcelona, 08028 Barcelona, Spain
- ICREA-Institucio Catalana de Recerca i Estudis Avancats, 08010 Barcelona, Spain
| | - Andrea Scotti
- Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany
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22
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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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23
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Shamana H, Dutcher JR. Transition in the Glassy Dynamics of Melts of Acid-Hydrolyzed Phytoglycogen Nanoparticles. Biomacromolecules 2022; 23:2040-2050. [PMID: 35390260 DOI: 10.1021/acs.biomac.2c00046] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The deformability, responsiveness, and tunability of soft nanoparticles (NPs) offer unique opportunities to learn about their complex properties and the interactions between particles. In the present study, we provide new insights into the physical properties of phytoglycogen (PG) NPs, which are soft, compact particles with a dendritic architecture that are produced in the kernels of sweet corn. In particular, we study PG NPs modified using acid hydrolysis, which not only reduces their diameter but also alters their stiffness, internal structure, and the interactions between particles in aqueous dispersions. We used steady shear rheology to determine the dependence of the relative zero-shear viscosity ηr of aqueous dispersions of acid-hydrolyzed PG NPs on the effective volume fraction ϕeff, which indicated a reduction in stiffness of the particles relative to that of native PG NPs. We quantified this difference by analyzing the nature of the colloidal glasses formed at high ϕeff. We measured a smaller value of the fragility index m for acid-hydrolyzed PG NP glasses than that for native PG NP glasses, indicating that acid-hydrolyzed PG NPs form stronger glasses and are therefore softer than native PG NPs. Unlike the native PG NPs, we observed a distinctive change in the character of the glass transition of the acid-hydrolyzed PG NPs as ϕeff was increased above ϕeff∼1: a crossover in the dependence of ηr on ϕeff from Vogel-Fulcher-Tammann behavior to a more gradual, Arrhenius-like behavior. By expressing the steady shear and oscillatory rheology data in terms of generalized Péclet numbers, we obtained collapse of the data onto master curves. We interpret this result in terms of the acid-hydrolyzed PG NPs predominantly interpenetrating neighboring particles at large ϕeff, for which fluctuations of the outer chains enhance the mobility of the particles and make α-relaxation times τα experimentally accessible.
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Affiliation(s)
- Hurmiz Shamana
- Department of Physics, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - John R Dutcher
- Department of Physics, University of Guelph, Guelph, ON N1G 2W1, Canada
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24
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Höfken T, Strauch C, Schneider S, Scotti A. Changes in the Form Factor and Size Distribution of Nanogels in Crowded Environments. NANO LETTERS 2022; 22:2412-2418. [PMID: 35258981 DOI: 10.1021/acs.nanolett.2c00120] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Particle size disparities suppress crystallization. However, soft deformable nanogels can change the size of the larger particles in suspension and crystallize even at a high initial size-polydispersity. Using neutron scattering with contrast variation, the response of individual nanogels in crowded environments was probed, and an increase of the parameter describing size-polydispersity was found, which is often interpreted as deformation. Here, computer simulations are used to generate deformed nanogels and the corresponding form factor. The data are fitted with the spherical model used to analyze scattering data. The fits show the same qualitative increase of the parameter related to the size-polydispersity with increasing particle deformation. Starting from the simulated deformed spheres, we also reproduce experimental scattering data. A further analysis of the particle shows that the size disparities between nanogels do not increase significantly. In contrast, their shapes strongly vary from one nanogel to the other.
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Affiliation(s)
- Tom Höfken
- Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany
| | - Christian Strauch
- Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany
| | - Stefanie Schneider
- 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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25
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Rheology Applied to Microgels: Brief (Revision of the) State of the Art. Polymers (Basel) 2022; 14:polym14071279. [PMID: 35406152 PMCID: PMC9003433 DOI: 10.3390/polym14071279] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 03/18/2022] [Accepted: 03/18/2022] [Indexed: 12/10/2022] Open
Abstract
The ability of polymer microgels to rapidly respond to external stimuli is of great interest in sensors, lubricants, and biomedical applications, among others. In most of their uses, microgels are subjected to shear, deformation, and compression forces or a combination of them, leading to variations in their rheological properties. This review article mainly refers to the rheology of microgels, from the hard sphere versus soft particles' model. It clearly describes the scaling theories and fractal structure formation, in particular, the Shih et al. and Wu and Morbidelli models as a tool to determine the interactions among microgel particles and, thus, the viscoelastic properties. Additionally, the most recent advances on the characterization of microgels' single-particle interactions are also described. The review starts with the definition of microgels, and a brief introduction addresses the preparation and applications of microgels and hybrid microgels.
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26
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Giliomee J, du Toit LC, Klumperman B, Choonara YE. Investigation of the 3D Printability of Covalently Cross-Linked Polypeptide-Based Hydrogels. ACS OMEGA 2022; 7:7556-7571. [PMID: 35284718 PMCID: PMC8908529 DOI: 10.1021/acsomega.1c05873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Accepted: 01/25/2022] [Indexed: 06/14/2023]
Abstract
The 3D printability of poly(l-lysine-ran-l-alanine) and four-arm poly(ethylene glycol) (P(KA)/4-PEG) hydrogels as 3D biomaterial inks was investigated using two approaches to develop P(KA)/4-PEG into 3D biomaterial inks. Only the "composite microgel" inks were 3D printable. In this approach, P(KA)/4-PEG hydrogels were processed into microparticles and incorporated into a polymer solution to produce a composite microgel paste. Polymer solutions composed of either 4-arm PEG-acrylate (4-PEG-Ac), chitosan (CS), or poly(vinyl alcohol) (PVA) were used as the matrix material for the composite paste. The three respective composite microgel inks displayed good 3D printability in terms of extrudability, layer-stacking ability, solidification mechanism, and 3D print fidelity. The biocompatibility of P(KA)/4-PEG hydrogels was retained in the 3D printed scaffolds, and the biofunctionality of bioinert 4-PEG and PVA hydrogels was enhanced. CS-P(KA)/4-PEG inks demonstrated excellent 3D printability and proved highly successful in printing scaffolds with a narrow strand diameter (∼200 μm) and narrow strand spacing (∼500 μm) while the integrity of the vertical and horizontal pores was maintained. Using different needle IDs and strand spacing, certain physical properties of the hydrogels could be tuned, while the 3D printed porosity was kept constant. This included the surface area to volume ratio, the macropore sizes, and the mechanical properties. The scaffolds demonstrated adequate adhesion and spreading of NIH 3T3 fibroblasts seeded on the scaffold surfaces for 4 days. Consequently, the scaffolds were considered suitable for potential applications in wound healing, as well as other soft tissue engineering applications. Apart from the contribution to new 3D biomaterial inks, this work also presented a new and facile method of processing covalently cross-linked hydrogels into 3D printed scaffolds. This could potentially "unlock" the 3D printability of biofunctional hydrogels, which are generally excluded from 3D printing applications.
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Affiliation(s)
- Johnel Giliomee
- Wits
Advanced Drug Delivery Platform Research Unit, Department of Pharmacy
and Pharmacology, School of Therapeutic Sciences, Faculty of Health
Sciences, University of the Witwatersrand, 7 York Road, Parktown, Johannesburg 2193, South
Africa
| | - Lisa C. du Toit
- Wits
Advanced Drug Delivery Platform Research Unit, Department of Pharmacy
and Pharmacology, School of Therapeutic Sciences, Faculty of Health
Sciences, University of the Witwatersrand, 7 York Road, Parktown, Johannesburg 2193, South
Africa
| | - Bert Klumperman
- Department
of Chemistry and Polymer Science, Faculty of Science, Stellenbosch University, De Beers Street, Stellenbosch 7600, South Africa
| | - Yahya E. Choonara
- Wits
Advanced Drug Delivery Platform Research Unit, Department of Pharmacy
and Pharmacology, School of Therapeutic Sciences, Faculty of Health
Sciences, University of the Witwatersrand, 7 York Road, Parktown, Johannesburg 2193, South
Africa
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27
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Lapkin D, Mukharamova N, Assalauova D, Dubinina S, Stellhorn J, Westermeier F, Lazarev S, Sprung M, Karg M, Vartanyants IA, Meijer JM. In situ characterization of crystallization and melting of soft, thermoresponsive microgels by small-angle X-ray scattering. SOFT MATTER 2022; 18:1591-1602. [PMID: 34994372 PMCID: PMC8864529 DOI: 10.1039/d1sm01537k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Depending on the volume fraction and interparticle interactions, colloidal suspensions can form different phases, ranging from fluids, crystals, and glasses to gels. For soft microgels that are made from thermoresponsive polymers, the volume fraction can be tuned by temperature, making them excellent systems to experimentally study phase transitions in dense colloidal suspensions. However, investigations of phase transitions at high particle concentration and across the volume phase transition temperature in particular, are challenging due to the deformability and possibility for interpenetration between microgels. Here, we investigate the dense phases of composite core-shell microgels that have a small gold core and a thermoresponsive microgel shell. Employing Ultra Small-Angle X-ray Scattering, we make use of the strong scattering signal from the gold cores with respect to the almost negligible signal from the shells. By changing the temperature we study the freezing and melting transitions of the system in situ. Using Bragg peak analysis and the Williamson-Hall method, we characterize the phase transitions in detail. We show that the system crystallizes into an rhcp structure with different degrees of in-plane and out-of-plane stacking disorder that increase upon particle swelling. We further find that the melting process is distinctly different, where the system separates into two different crystal phases with different melting temperatures and interparticle interactions.
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Affiliation(s)
- Dmitry Lapkin
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany
| | | | - Dameli Assalauova
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany
| | - Svetlana Dubinina
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany
- Moscow Institute of Physics and Technology (State University), Institutskiy Per. 9, 141701 Dolgoprudny, Moscow Region, Russia
| | - Jens Stellhorn
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany
- Department of Applied Chemistry, Graduate School of Advanced Science and Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashihiroshima 739-8527, Japan
| | - Fabian Westermeier
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany
| | - Sergey Lazarev
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany
- National Research Tomsk Polytechnic University (TPU), Lenin Avenue 30, 634050 Tomsk, Russia
| | - Michael Sprung
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany
| | - Matthias Karg
- Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, D-40225 Düsseldorf, Germany
| | - Ivan A Vartanyants
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany
- National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Kashirskoe shosse 31, 115409 Moscow, Russia.
| | - Janne-Mieke Meijer
- Department of Applied Physics and Institute for Complex Molecular Systems, Eindhoven University of Technology, Groene Loper 19, 5612 AP Eindhoven, The Netherlands.
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28
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Romero-Sanchez I, Pihlajamaa I, Adžić N, Castellano LE, Stiakakis E, Likos CN, Laurati M. Blunt-End Driven Re-entrant Ordering in Quasi Two-Dimensional Dispersions of Spherical DNA Brushes. ACS NANO 2022; 16:2133-2146. [PMID: 35130432 PMCID: PMC8867906 DOI: 10.1021/acsnano.1c07799] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
We investigate the effects of crowding on the conformations and assembly of confined, highly charged, and thick polyelectrolyte brushes in the osmotic regime. Particle tracking experiments on increasingly dense suspensions of colloids coated with ultralong double-stranded DNA (dsDNA) fragments reveal nonmonotonic particle shrinking, aggregation, and re-entrant ordering. Theory and simulations show that aggregation and re-entrant ordering arise from the combined effect of shrinking, which is induced by the osmotic pressure exerted by the counterions absorbed in neighbor brushes and of a short-range attractive interaction competing with electrostatic repulsion. An unconventional mechanism gives origin to the short-range attraction: blunt-end interactions between stretched dsDNA fragments of neighboring brushes, which become sufficiently intense for dense and packed brushes. The attraction can be tuned by inducing free-end backfolding through the addition of monovalent salt. Our results show that base stacking is a mode parallel to hybridization to steer colloidal assembly in which attractions can be fine-tuned through salinity and, potentially, grafting density and temperature.
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Affiliation(s)
- Ivany Romero-Sanchez
- Dipartimento
di Chimica & CSGI, Università
di Firenze, 50019 Sesto Fiorentino, Italy
- División
de Ciencias e Ingenierías, Universidad
de Guanajuato, 37150 León, Mexico
| | - Ilian Pihlajamaa
- Faculty
of Physics, University of Vienna, Bolzmanngasse 5, A-1090 Vienna, Austria
- Eindhoven
University of Technology, Department of
Applied Physics, Soft Matter and Biological Physics, Postbus 513, NL-5600 MB Eindhoven, The Netherlands
| | - Natasa Adžić
- Faculty
of Physics, University of Vienna, Bolzmanngasse 5, A-1090 Vienna, Austria
| | - Laura E. Castellano
- División
de Ciencias e Ingenierías, Universidad
de Guanajuato, 37150 León, Mexico
| | - Emmanuel Stiakakis
- Biomacromolecular
Systems and Processes, Institute of Biological Information Processing
(IBI-4), 4 Forschungszentrum Jülich, D-52425 Jülich, Germany
| | - Christos N. Likos
- Faculty
of Physics, University of Vienna, Bolzmanngasse 5, A-1090 Vienna, Austria
| | - Marco Laurati
- Dipartimento
di Chimica & CSGI, Università
di Firenze, 50019 Sesto Fiorentino, Italy
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29
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Zemła J, Iyer PS, Pyka-Fościak G, Mermod N, Lekka M. Rheological properties of skeletal muscles in a Duchenne muscular dystrophy murine model before and after autologous cell therapy. J Biomech 2021; 128:110770. [PMID: 34628203 DOI: 10.1016/j.jbiomech.2021.110770] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 08/30/2021] [Accepted: 09/22/2021] [Indexed: 12/25/2022]
Abstract
Duchenne muscular dystrophy (DMD) is still an incurable muscle degenerative disease; thus, numerous studies focused on novel therapeutic approaches. However, a simple assay of muscle function restoration remains needed. Herein, we used an oscillatory shear rheometer to evaluate changes in rheological properties of mouse muscles (tibialis anterior, TA) and their restoration upon autologous cell therapy by comparing the viscoelastic properties of normal, diseased and treated muscles. Amplitude sweep tests of muscle samples were performed under 20% compression over a range of shear strain between 0.01 and 2% and frequency of 1 rad/s. The samples were tested in plane-plane geometry and horizontal myofiber alignment. Typical linear viscoelastic region (LVER) patterns were found for each muscle type. For healthy muscles, a broad LVER between shear deformations (γ) of 0.013-0.62% was observed. The LVER of DMD mdx/SCID muscles was found at 0.14% to 0.46% shear deformation, and no shear dependence of storage (G') and loss (G") moduli at γ range changing from 0.034% to 0.26% was found for transplanted tissues. G'LVER and G"LVER moduli of healthy muscles were significantly higher than G'LVER and G"LVER of dystrophic tissues. Additionally, muscle resistance assessment by rheometer indicated that muscles transplanted with stem cells restored elastic properties to levels close to those of healthy muscles. Interestingly, histological staining and rheological data indicate that the loss factor is strongly related to structural changes of examined muscles.
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Affiliation(s)
- Joanna Zemła
- Institute of Nuclear Physics Polish Academy of Sciences, PL-31342 Krakow, Poland.
| | - Pavithra S Iyer
- Institute of Biotechnology and Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Grażyna Pyka-Fościak
- Department of Histology, Jagiellonian University Medical College, Kopernika 7, 31-034 Krakow, Poland
| | - Nicolas Mermod
- Institute of Biotechnology and Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Małgorzata Lekka
- Institute of Nuclear Physics Polish Academy of Sciences, PL-31342 Krakow, Poland
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30
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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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31
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Luo J, Zhu Y, Ruan Y, Wu W, Ouyang X, Du Z, Liu G. Diameter and Elasticity Governing the Relaxation of Soft-Nanoparticle Melts. Macromolecules 2021. [DOI: 10.1021/acs.macromol.1c01111] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jintian Luo
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Center for Advanced Low-dimension Materials, College of Material Science and Engineering, Donghua University, Shanghai 201620, China
| | - Yihui Zhu
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Center for Advanced Low-dimension Materials, College of Material Science and Engineering, Donghua University, Shanghai 201620, China
| | - Yifu Ruan
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Center for Advanced Low-dimension Materials, College of Material Science and Engineering, Donghua University, Shanghai 201620, China
| | - Weiwei Wu
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Center for Advanced Low-dimension Materials, College of Material Science and Engineering, Donghua University, Shanghai 201620, China
| | - Xikai Ouyang
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Center for Advanced Low-dimension Materials, College of Material Science and Engineering, Donghua University, Shanghai 201620, China
| | - Zhukang Du
- South China Advanced Institute for Soft Matter Science and Technology, School of Molecular Science and Engineering, South China University of Technology, Guangzhou 510640, China
| | - GengXin Liu
- State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Center for Advanced Low-dimension Materials, College of Material Science and Engineering, Donghua University, Shanghai 201620, China
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32
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Frenzel L, Dartsch M, Balaguer GM, Westermeier F, Grübel G, Lehmkühler F. Glass-liquid and glass-gel transitions of soft-shell particles. Phys Rev E 2021; 104:L012602. [PMID: 34412357 DOI: 10.1103/physreve.104.l012602] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Accepted: 06/23/2021] [Indexed: 12/12/2022]
Abstract
We study the structure and dynamics of colloidal particles with a spherical hard core and a thermo-responsive soft shell over the whole phase diagram by means of small-angle x-ray scattering and x-ray photon correlation spectroscopy. By changing the effective volume fraction by temperature and particle concentration, liquid, repulsive glass. and attractive gel phases are observed. The dynamics slow down with increasing volume fraction in the liquid phase and reflect a Vogel-Fulcher-Tamann behavior known for fragile glass formers. We find a liquid-glass transition above 50 vol.% that is independent of the particles' concentration and temperature. In an overpacked state at effective volume fractions above 1, the dispersion does not show a liquid phase but undergoes a gel-glass transition at an effective volume fraction of 34 vol.%. At the same concentration, extrema of subdiffusive dynamics are found in the liquid phase at lower weight fractions. We interpret this as dynamic precursors of the glass-gel transition.
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Affiliation(s)
- Lara Frenzel
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany.,The Hamburg Centre for Ultrafast Imaging, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Michael Dartsch
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany.,The Hamburg Centre for Ultrafast Imaging, Luruper Chaussee 149, 22761 Hamburg, Germany
| | | | - Fabian Westermeier
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany
| | - Gerhard Grübel
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany.,The Hamburg Centre for Ultrafast Imaging, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Felix Lehmkühler
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany.,The Hamburg Centre for Ultrafast Imaging, Luruper Chaussee 149, 22761 Hamburg, Germany
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33
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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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34
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Affiliation(s)
- Yuichiro Nishizawa
- Graduate School of Textile Science & Technology, Shinshu University, 3-15-1 Tokida, Ueda, Nagano 386-8567, Japan
| | - Kenshiro Honda
- 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
- Research Initiative for Supra-Materials, Interdisciplinary Cluster for Cutting Edge Research, Shinshu University, 3-15-1 Tokida, Ueda, Nagano 386-8567, Japan
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35
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Gnan N, Camerin F, Del Monte G, Ninarello A, Zaccarelli E. Dynamical properties of different models of elastic polymer rings: Confirming the link between deformation and fragility. J Chem Phys 2021; 154:154901. [PMID: 33887924 DOI: 10.1063/5.0041264] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
We report extensive numerical simulations of different models of 2D polymer rings with internal elasticity. We monitor the dynamical behavior of the rings as a function of the packing fraction to address the effects of particle deformation on the collective response of the system. In particular, we compare three different models: (i) a recently investigated model [N. Gnan and E. Zaccarelli, Nat. Phys. 15, 683 (2019)] where an inner Hertzian field providing the internal elasticity acts on the monomers of the ring, (ii) the same model where the effect of such a field on the center of mass is balanced by opposite forces, and (iii) a semi-flexible model where an angular potential between adjacent monomers induces strong particle deformations. By analyzing the dynamics of the three models, we find that in all cases, there exists a direct link between the system fragility and particle asphericity. Among the three, only the first model displays anomalous dynamics in the form of a super-diffusive behavior of the mean-squared displacement and of a compressed exponential relaxation of the density auto-correlation function. We show that this is due to the combination of internal elasticity and the out-of-equilibrium force self-generated by each ring, both of which are necessary ingredients to induce such a peculiar behavior often observed in experiments of colloidal gels. These findings reinforce the role of particle deformation, connected to internal elasticity, in driving the dynamical response of dense soft particles.
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Affiliation(s)
- Nicoletta Gnan
- CNR Institute for Complex Systems, Uos Sapienza, Piazzale Aldo Moro 2, 00185 Roma, Italy
| | - Fabrizio Camerin
- CNR Institute for Complex Systems, Uos Sapienza, Piazzale Aldo Moro 2, 00185 Roma, Italy
| | - Giovanni Del Monte
- CNR Institute for Complex Systems, Uos Sapienza, Piazzale Aldo Moro 2, 00185 Roma, Italy
| | - Andrea Ninarello
- CNR Institute for Complex Systems, Uos Sapienza, Piazzale Aldo Moro 2, 00185 Roma, Italy
| | - Emanuela Zaccarelli
- CNR Institute for Complex Systems, Uos Sapienza, Piazzale Aldo Moro 2, 00185 Roma, Italy
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36
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Glass and Jamming Rheology in Soft Particles Made of PNIPAM and Polyacrylic Acid. Int J Mol Sci 2021; 22:ijms22084032. [PMID: 33919803 PMCID: PMC8070831 DOI: 10.3390/ijms22084032] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 03/31/2021] [Accepted: 04/01/2021] [Indexed: 11/29/2022] Open
Abstract
The phase behaviour of soft colloids has attracted great attention due to the large variety of new phenomenologies emerging from their ability to pack at very high volume fractions. Here we report rheological measurements on interpenetrated polymer network microgels composed of poly(N-isopropylacrylamide) (PNIPAM) and polyacrylic acid (PAAc) at fixed PAAc content as a function of weight concentration. We found three different rheological regimes characteristic of three different states: a Newtonian shear-thinning fluid, an attractive glass characterized by a yield stress, and a jamming state. We discuss the possible molecular mechanisms driving the formation of these states.
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37
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Shangwei L, Urakawa O, Inoue T. Rheo-Optical Study on the Viscoelastic Relaxation Modes of a Microgel Particle Suspension around the Liquid–Solid Transition Regime. Macromolecules 2021. [DOI: 10.1021/acs.macromol.0c02205] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Li Shangwei
- Department of Macromolecular Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan
| | - Osamu Urakawa
- Department of Macromolecular Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan
| | - Tadashi Inoue
- Department of Macromolecular Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan
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38
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Nishizawa Y, Minato H, Inui T, Saito I, Kureha T, Shibayama M, Uchihashi T, Suzuki D. Nanostructure and thermoresponsiveness of poly( N-isopropyl methacrylamide)-based hydrogel microspheres prepared via aqueous free radical precipitation polymerization. RSC Adv 2021; 11:13130-13137. [PMID: 35423887 PMCID: PMC8697349 DOI: 10.1039/d1ra01650d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 03/28/2021] [Indexed: 01/13/2023] Open
Abstract
Thermoresponsive hydrogel microspheres (microgels) are smart materials that quickly respond to external stimuli, and their thermoresponsiveness can be tuned by varying the constituent chemical species. Although uniformly sized microgels can be prepared via aqueous free radical precipitation polymerization, the nanostructure of the obtained microgels is complex and remains unclear so far. In the present study, the nanostructure and thermoresponsiveness of poly(N-isopropyl methacrylamide) (pNIPMAm)-based microgels, which have a volume-transition temperature of ∼43 °C, were evaluated mainly using temperature-controllable high-speed atomic force microscopy. These observations, which are characterized by high spatio-temporal resolution, revealed that the pNIPMAm microgels have a peculiar heterogeneous structure, for example a core-shell and non-thermoresponsive nanostructure in the core region, that originates from the precipitation polymerization process. Furthermore, it was found that the adsorption concentration of the microgels on the substrate is one of the keys for controlling their thermoresponsiveness. These findings can be expected to advance the design of new materials such as thermoresponsive nanosheets and stimuli-responsive coatings.
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Affiliation(s)
- Yuichiro Nishizawa
- Graduate School of Textile Science & Technology, Shinshu University 3-15-1 Tokida Ueda Nagano 386-8567 Japan
| | - Haruka Minato
- Graduate School of Textile Science & Technology, Shinshu University 3-15-1 Tokida Ueda Nagano 386-8567 Japan
| | - Takumi Inui
- Graduate School of Textile Science & Technology, Shinshu University 3-15-1 Tokida Ueda Nagano 386-8567 Japan
| | - Ikuma Saito
- Graduate School of Textile Science & Technology, Shinshu University 3-15-1 Tokida Ueda Nagano 386-8567 Japan
| | - Takuma Kureha
- Graduate School of Science & Technology, Hirosaki University 3, Bunkyo-cho, Hirosaki Aomori 036-8561 Japan
| | - Mitsuhiro Shibayama
- Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society 162-1 Shirakata Tokai Ibaraki 319-1106 Japan
| | - Takayuki Uchihashi
- Department of Physics, Structural Biology Research Center, Graduate School of Science, Nagoya University Furo-cho, Chiksusa-ku Nagoya Aichi 464-8602 Japan
- Exploratory Research Center on Life and Living Systems, National Institutes of Natural Science 5-1 Higashiyama, Myodaiji Okazaki Aichi 444-8787 Japan
| | - Daisuke Suzuki
- Graduate School of Textile Science & Technology, Shinshu University 3-15-1 Tokida Ueda Nagano 386-8567 Japan
- Research Initiative for Supra-Materials, Interdisciplinary Cluster for Cutting Edge Research, Shinshu University 3-15-1 Tokida Ueda Nagano 386-8567 Japan
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Effect of D-Mannitol on the Microstructure and Rheology of Non-Aqueous Carbopol Microgels. MATERIALS 2021; 14:ma14071782. [PMID: 33916550 PMCID: PMC8038445 DOI: 10.3390/ma14071782] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 03/31/2021] [Accepted: 04/01/2021] [Indexed: 11/17/2022]
Abstract
D-mannitol is a common polyol that is used as additive in pharmaceutical and personal care product formulations. We investigated its effect on the microstructure and rheology of novel non-aqueous Carbopol dispersions employing traditional and time-resolved rheological analysis. We considered two types of sample, (i) fresh (i.e., mannitol completely dissolved in solution) and aged (i.e., visible in crystalline form). The analysis of the intracycle rheological transitions that were observed for different samples revealed that, when completely dissolved in solution, mannitol does not alter the rheological behaviour of the Carbopol dispersions. This highlights that the chemical similarity of the additive with the molecules of the surrounding solvent allows preserving the swollen dimension and interparticle interactions of the Carbopol molecules. Conversely, when crystals are present, a hierarchical structure forms, consisting of a small dispersed phase (Carbopol) agglomerated around a big dispersed phase (crystals). In keeping with this microstructural picture, as the concentration of Carbopol reduces, the local dynamics of the crystals gradually start to control the integrity of the microstructure. Rheologically, this results in a higher elasticity of the suspensions at infinitesimal deformations, but a fragile yielding process at intermediate strains.
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40
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Colloidal and polymeric contributions to the yielding of dense microgel suspensions. J Colloid Interface Sci 2021; 587:437-445. [DOI: 10.1016/j.jcis.2020.11.101] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 11/06/2020] [Accepted: 11/25/2020] [Indexed: 11/21/2022]
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Del Monte G, Camerin F, Ninarello A, Gnan N, Rovigatti L, Zaccarelli E. Charge affinity and solvent effects in numerical simulations of ionic microgels. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:084001. [PMID: 33105117 DOI: 10.1088/1361-648x/abc4cb] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Ionic microgel particles are intriguing systems in which the properties of thermo-responsive polymeric colloids are enriched by the presence of charged groups. In order to rationalize their properties and predict the behaviour of microgel suspensions, it is necessary to develop a coarse-graining strategy that starts from the accurate modelling of single particles. Here, we provide a numerical advancement of a recently-introduced model for charged co-polymerized microgels by improving the treatment of ionic groups in the polymer network. We investigate the thermoresponsive properties of the particles, in particular their swelling behaviour and structure, finding that, when charged groups are considered to be hydrophilic at all temperatures, highly charged microgels do not achieve a fully collapsed state, in favorable comparison to experiments. In addition, we explicitly include the solvent in the description and put forward a mapping between the solvophobic potential in the absence of the solvent and the monomer-solvent interactions in its presence, which is found to work very accurately for any charge fraction of the microgel. Our work paves the way for comparing single-particle properties and swelling behaviour of ionic microgels to experiments and to tackle the study of these charged soft particles at a liquid-liquid interface.
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Affiliation(s)
- Giovanni Del Monte
- CNR Institute of Complex Systems, Uos Sapienza, Piazzale Aldo Moro 2, 00185, Roma, Italy
- Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 2, 00185 Roma, Italy
- Center for Life NanoScience, Istituto Italiano di Tecnologia, Viale Regina Elena 291, 00161 Rome, Italy
| | - Fabrizio Camerin
- CNR Institute of Complex Systems, Uos Sapienza, Piazzale Aldo Moro 2, 00185, Roma, Italy
- Department of Basic and Applied Sciences for Engineering, Sapienza University of Rome, via Antonio Scarpa 14, 00161 Roma, Italy
| | - Andrea Ninarello
- CNR Institute of Complex Systems, Uos Sapienza, Piazzale Aldo Moro 2, 00185, Roma, Italy
- Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 2, 00185 Roma, Italy
| | - Nicoletta Gnan
- CNR Institute of Complex Systems, Uos Sapienza, Piazzale Aldo Moro 2, 00185, Roma, Italy
- Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 2, 00185 Roma, Italy
| | - Lorenzo Rovigatti
- CNR Institute of Complex Systems, Uos Sapienza, Piazzale Aldo Moro 2, 00185, Roma, Italy
- Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 2, 00185 Roma, Italy
| | - Emanuela Zaccarelli
- CNR Institute of Complex Systems, Uos Sapienza, Piazzale Aldo Moro 2, 00185, Roma, Italy
- Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 2, 00185 Roma, Italy
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Schulte MF, Bochenek S, Brugnoni M, Scotti A, Mourran A, Richtering W. Stiffness Tomography of Ultra-Soft Nanogels by Atomic Force Microscopy. Angew Chem Int Ed Engl 2021; 60:2280-2287. [PMID: 33459462 PMCID: PMC7898630 DOI: 10.1002/anie.202011615] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Indexed: 01/02/2023]
Abstract
The softness of nanohydrogels results in unique properties and recently attracted tremendous interest due to the multi-functionalization of interfaces. Herein, we study extremely soft temperature-sensitive ultra-low cross-linked (ULC) nanogels adsorbed to the solid/water interface by atomic force microscopy (AFM). The ultra-soft nanogels seem to disappear in classical imaging modes since a sharp tip fully penetrates these porous networks with very low forces in the range of steric interactions (ca. 100 pN). However, the detailed evaluation of Force Volume mode measurements allows us to resolve their overall shape and at the same time their internal structure in all three dimensions. The nanogels exhibit an extraordinary disk-like and entirely homogeneous but extremely soft structure-even softer than polymer brushes. Moreover, the temperature-sensitive nanogels can be switched on demand between the ultra-soft and a very stiff state.
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Affiliation(s)
| | - Steffen Bochenek
- Institute of Physical ChemistryRWTH Aachen UniversityLandoltweg 252056AachenGermany
| | - Monia Brugnoni
- Institute of Physical ChemistryRWTH Aachen UniversityLandoltweg 252056AachenGermany
| | - Andrea Scotti
- Institute of Physical ChemistryRWTH Aachen UniversityLandoltweg 252056AachenGermany
| | - Ahmed Mourran
- DWI—Leibniz Institute for Interactive MaterialsForckenbeckstr. 5052056AachenGermany
| | - Walter Richtering
- Institute of Physical ChemistryRWTH Aachen UniversityLandoltweg 252056AachenGermany
- DWI—Leibniz Institute for Interactive MaterialsForckenbeckstr. 5052056AachenGermany
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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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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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Microstructure-driven self-assembly and rheological properties of multi-responsive soft microgel suspensions. J Colloid Interface Sci 2021; 581:806-815. [PMID: 32814199 DOI: 10.1016/j.jcis.2020.07.137] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2020] [Revised: 07/26/2020] [Accepted: 07/27/2020] [Indexed: 01/23/2023]
Abstract
HYPOTHESES The deformation and swelling ability of microgels is influenced by the crosslinking distribution. Varying microgels microstructure is expected to obtain suspensions with different flow behavior and thereby, different rheological properties. EXPERIMENTS Different multi-responsive microgels were synthesized using two different crosslinkers and varying their amounts: N,N-methylene bis-acrylamide (MBA) and oligo(ethylene glycol) diacrylate (OEGDA). The rheological results were obtained by zero-shear viscosity and long-time creep measurements on concentrated microgel suspensions Microgel microstructure was analyzed by 1H nuclear magnetic resonance transverse relaxation measurements. FINDINGS At a constant crosslinking rate, we show that the viscosity of OEGDA-crosslinked microgels diverges at a higher concentration than MBA ones, suggesting a looser shell and less restricted dangling chains at the periphery for the later. By scaling with the effective volume fraction, the viscosity curves of the different microgel suspensions reduce into a single curve and closely follow hard sphere models up to ϕeff < 0.45. The results from creep tests revealed a much higher yield stress for MBA-crosslinked microgels, strengthening the hypothesis of a looser shell for the later. Finally, transverse relaxation (T2) NMR measurements demonstrated that, although all microgels exhibit a core-shell microstructure, MBA samples present a less crosslinked shell corroborating with the rheological results.
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Sruthi L, Srivastava V, Schmidt LE, Deshpande AP, Varughese S. Contributions from microstructural changes to the rheological behavior of casein dispersions during drying. SOFT MATTER 2020; 16:10954-10968. [PMID: 33146222 DOI: 10.1039/d0sm00992j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
In several applications, a protein such as casein in dispersion form undergoes multiple processing steps including drying. In this work, the rheological and microstructural features of casein dispersions concentrated by evaporation of the solvent (drying dispersions) were studied in comparison with those of equal concentrations of the as-prepared dispersions without drying. The molecular assembly of casein is affected by drying along with the conformational composition changes in the secondary structures such as α-helix, β-sheets, turns and random structures of the protein. Modeling of the rheological data indicates that these changes also affect the packing of casein molecular assemblies and these molecular assemblies in alkaline dispersions can behave as soft deformable particles. During drying, casein dispersions show prominent shear thinning for concentrations higher than 20 wt% along with the prevalence of α-helices and β-sheets. In comparison, the as-prepared dispersions show different microstructural features, and therefore different rheological responses. A detailed analysis shows that alkalinity changes during drying is the crucial factor controlling the microstructural changes of the soft casein particles and hence the rheology.
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Affiliation(s)
- Lalitha Sruthi
- Department of Chemical Engineering, Indian Institute of Technology, Madras, India.
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47
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Schulte MF, Bochenek S, Brugnoni M, Scotti A, Mourran A, Richtering W. Stiffness Tomography of Ultra‐Soft Nanogels by Atomic Force Microscopy. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202011615] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- M. Friederike Schulte
- Institute of Physical Chemistry RWTH Aachen University Landoltweg 2 52056 Aachen Germany
| | - Steffen Bochenek
- Institute of Physical Chemistry RWTH Aachen University Landoltweg 2 52056 Aachen Germany
| | - Monia Brugnoni
- Institute of Physical Chemistry RWTH Aachen University Landoltweg 2 52056 Aachen Germany
| | - Andrea Scotti
- Institute of Physical Chemistry RWTH Aachen University Landoltweg 2 52056 Aachen Germany
| | - Ahmed Mourran
- DWI—Leibniz Institute for Interactive Materials Forckenbeckstr. 50 52056 Aachen Germany
| | - Walter Richtering
- Institute of Physical Chemistry RWTH Aachen University Landoltweg 2 52056 Aachen Germany
- DWI—Leibniz Institute for Interactive Materials Forckenbeckstr. 50 52056 Aachen Germany
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48
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49
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Migliozzi S, Meridiano G, Angeli P, Mazzei L. Investigation of the swollen state of Carbopol molecules in non-aqueous solvents through rheological characterization. SOFT MATTER 2020; 16:9799-9815. [PMID: 33005911 DOI: 10.1039/d0sm01196g] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We explore how different types of solvent influence the rheological properties of non-aqueous Carbopol dispersions from the dilute to the jammed state. In novel non-aqueous formulations, polar solvents are used more and more frequently, because they can form Carbopol microgels without the need of any neutralizing agents. However, the swelling behaviour of Carbopol molecules in the absence of water, when ionic forces are weak, is still poorly understood. To this end, we study the swelling behaviour of Carbopol 974P NF in different polar solvents, i.e. glycerol, PEG400 and mixtures of the two solvents, by mapping the rheological behaviour of Carbopol suspensions from very dilute to highly concentrated conditions. The rheological study reveals that the onset of the jamming transition occurs at different critical polymer concentrations depending on the solvents used. Nevertheless, once the jammed state is reached, both elastic and yielding behaviours are scalable with the particle volume fraction. These results suggest that the type of solvent influences the final volume of the single Carbopol particles but does not alter the interactions between the particles. The final radius of the swollen particles is estimated from shear rheology measurements in dilute conditions, showing a decrease of the final swelling ratio of Carbopol molecules of almost 50% for PEG400 solutions, a result that confirms the shift to higher values of the critical jamming concentration obtained from linear viscoelasticity for the same solutions.
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Affiliation(s)
- Simona Migliozzi
- Department of Chemical Engineering, University College London, Torrington Place, London WC1E 7JE, UK.
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50
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Scotti A, Houston JE, Brugnoni M, Schmidt MM, Schulte MF, Bochenek S, Schweins R, Feoktystov A, Radulescu A, Richtering W. Phase behavior of ultrasoft spheres show stable bcc lattices. Phys Rev E 2020; 102:052602. [PMID: 33327194 DOI: 10.1103/physreve.102.052602] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Accepted: 10/01/2020] [Indexed: 06/12/2023]
Abstract
The phase behavior of supersoft spheres is explored using solutions of ultralow cross-linked poly(N-isopropylacrylamide)-based microgels as a model system. For these microgels, the effects of the electric charges on their surfaces can be neglected and therefore only the role of softness on the phase behavior is investigated. The samples show a liquid-to-crystal transition at higher volume fraction with respect to both hard spheres and stiffer microgels. Furthermore, stable body centered cubic (bcc) crystals are observed in addition to the expected face centered cubic (fcc) crystals. Small-angle x-ray and neutron scattering with contrast variation allow the characterization of both the microgel-to-microgel distance and the architecture of single microgels in crowded solutions. The measurements reveal that the stable bcc crystals depend on the interplay between the collapse and the interpenetration of the external shell of the ultralow cross-linked microgels.
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Affiliation(s)
- A Scotti
- Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany
| | - J E Houston
- European Spallation Source ERIC, Box 176, SE-221 00 Lund, Sweden
| | - M Brugnoni
- Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany
| | - M M Schmidt
- Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany
| | - M F Schulte
- Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany
| | - S Bochenek
- 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
| | - A Feoktystov
- Forschungszentrum Jülich GmbH, Jülich Centre for Neutron Science JCNS at Heinz Maier-Leibnitz Zentrum MLZ, 85748 Garching, Germany
| | - A Radulescu
- Forschungszentrum Jülich GmbH, Jülich Centre for Neutron Science JCNS at Heinz Maier-Leibnitz Zentrum MLZ, 85748 Garching, Germany
| | - W Richtering
- Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany
- JARA-SOFT, 52056 Aachen, Germany
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