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Hoppe Alvarez L, Rudov AA, Gumerov RA, Lenssen P, Simon U, Potemkin II, Wöll D. Controlling microgel deformation via deposition method and surface functionalization of solid supports. Phys Chem Chem Phys 2021; 23:4927-4934. [PMID: 33620358 DOI: 10.1039/d0cp06355j] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Soft matter at solid-liquid interfaces plays an important role in multiple scientific disciplines as well as in various technological fields. For microgels, representing highly interesting soft matter systems, we demonstrate that the preparation method, i.e. the way how the microgel is applied to the specific surface, plays a key role. Focusing on the three most common sample preparation methods (spin-coating, drop-casting and adsorption from solution), we performed a comparative study of the deformation behavior of microgels at the solid-liquid interface on three different surfaces with varying hydrophilicities. For in situ visualization of the deformation of pNIPMAM microgels, we conducted highly sensitive 3D super resolution fluorescence microscopy methods. We furthermore performed complementary molecular dynamics simulations to determine the driving force responsible for the deformation depending on the surface and the deposition method. The combination of experiments and simulations revealed that the simulated equilibrium structure obtained after simulation of the completely dry microgel after deposition is retained after rehydration and subsequent fluorescent imaging.
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Affiliation(s)
- Laura Hoppe Alvarez
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, D-52056 Aachen, Germany.
| | - Andrey A Rudov
- Physics Department, Lomonosov Moscow State University, Leninskie Gory 1-2, Moscow 119991, Russian Federation and DWI - Leibniz-Institute for Interactive Materials, Forckenbeckstraße 50, D-52056 Aachen, Germany
| | - Rustam A Gumerov
- Physics Department, Lomonosov Moscow State University, Leninskie Gory 1-2, Moscow 119991, Russian Federation and DWI - Leibniz-Institute for Interactive Materials, Forckenbeckstraße 50, D-52056 Aachen, Germany
| | - Pia Lenssen
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, D-52056 Aachen, Germany.
| | - Ulrich Simon
- Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1 a, D-52056 Aachen, Germany
| | - Igor I Potemkin
- Physics Department, Lomonosov Moscow State University, Leninskie Gory 1-2, Moscow 119991, Russian Federation and DWI - Leibniz-Institute for Interactive Materials, Forckenbeckstraße 50, D-52056 Aachen, Germany and National Research South Ural State University, Chelyabinsk 454080, Russian Federation
| | - Dominik Wöll
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, D-52056 Aachen, Germany.
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52
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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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53
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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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54
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Solin K, Beaumont M, Rosenfeldt S, Orelma H, Borghei M, Bacher M, Opietnik M, Rojas OJ. Self-Assembly of Soft Cellulose Nanospheres into Colloidal Gel Layers with Enhanced Protein Adsorption Capability for Next-Generation Immunoassays. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2020; 16:e2004702. [PMID: 33215868 DOI: 10.1002/smll.202004702] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 10/20/2020] [Indexed: 06/11/2023]
Abstract
Soft cationic core/shell cellulose nanospheres can deform and interpenetrate allowing their self-assembly into densely packed colloidal nanogel layers. Taking advantage of their water-swelling capacity and molecular accessibility, the nanogels are proposed as a new and promising type of coating material to immobilize bioactive molecules on thin films and paper. The specific and nonspecific interactions between the cellulosic nanogel and human immunoglobulin G as well as bovine serum albumin (BSA) are investigated. Confocal microscopy, electroacoustic microgravimetry, and surface plasmon resonance are used to access information about the adsorption behavior and viscoelastic properties of self-assembled nanogels. A significant BSA adsorption capacity on nanogel layers (17 mg m-2 ) is measured, 300% higher compared to typical polymer coatings. This high protein affinity further confirms the promise of the introduced colloidal gel layer, in increasing sensitivity and advancing a new generation of substrates for a variety of applications, including immunoassays, as demonstrated in this work.
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Affiliation(s)
- Katariina Solin
- Department of Bioproducts and Biosystems, School of Chemical Engineering, Aalto University, Vuorimiehentie 1, Espoo, FI-00076, Finland
| | - Marco Beaumont
- Department of Bioproducts and Biosystems, School of Chemical Engineering, Aalto University, Vuorimiehentie 1, Espoo, FI-00076, Finland
- Department of Chemistry, Institute of Chemistry for Renewable Resources, University of Natural Resources and Life Sciences Vienna (BOKU), Konrad-Lorenz-Strasse 24, Tulln, A-3430, Austria
| | - Sabine Rosenfeldt
- Bavarian Polymer Institute and Department of Chemistry, University of Bayreuth, Bayreuth, D-95440, Germany
| | - Hannes Orelma
- VTT - Technical Research Centre of Finland, Tietotie 4E, P.O. Box 1000, Espoo, FI-02044, Finland
| | - Maryam Borghei
- Department of Bioproducts and Biosystems, School of Chemical Engineering, Aalto University, Vuorimiehentie 1, Espoo, FI-00076, Finland
| | - Markus Bacher
- Department of Chemistry, Institute of Chemistry for Renewable Resources, University of Natural Resources and Life Sciences Vienna (BOKU), Konrad-Lorenz-Strasse 24, Tulln, A-3430, Austria
| | | | - Orlando J Rojas
- Department of Bioproducts and Biosystems, School of Chemical Engineering, Aalto University, Vuorimiehentie 1, Espoo, FI-00076, Finland
- The Bioproducts Institute, Department of Chemical and Biological Engineering, and Department of Chemistry and Wood Science, University of British Columbia, 2360 East Mall, Vancouver, BC, V6T 1Z4, Canada
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Buratti E, Sanzari I, Dinelli F, Prodromakis T, Bertoldo M. Formation and Stability of Smooth Thin Films with Soft Microgels Made of Poly( N-Isopropylacrylamide) and Poly(Acrylic Acid). Polymers (Basel) 2020; 12:E2638. [PMID: 33182647 PMCID: PMC7697199 DOI: 10.3390/polym12112638] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 10/29/2020] [Accepted: 11/05/2020] [Indexed: 11/30/2022] Open
Abstract
In this work, soft microgels of Poly(N-Isopropylacrylamide) (PNIPAm) at two different sizes and of interpenetrated polymer network (IPN) composed of PNIPAm and Poly(Acrylic Acid) (PAAc) were synthesized. Then, solutions of these different types of microgels have been spin-coated on glass substrates with different degrees of hydrophobicity. PNIPAm particles with a larger diameter form either patches or a continuous layer, where individual particles are still distinct, depending on the dispersion concentration and spin speed. On the other, PNIPAm particles with a smaller diameter and IPN particles form a continuous and smooth film, with a thickness depending on the dispersion concentration and spin-speed. The difference in morphology observed can be explained if one considers that the microgels may behave as colloidal particles or macromolecules, depending on their size and composition. Additionally, the microgel size and composition can also affect the stability of the depositions when rinsed in water. In particular, we find that the smooth and continuous films show a stimuli-dependent stability on parameters such as temperature and pH, while large particle layers are stable under any condition except on hydrophilic glass by washing at 50 °C.
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Affiliation(s)
- Elena Buratti
- Istituto per i Processi Chimico Fisici del Consiglio Nazionale delle Ricerche (IPCF-CNR), sede di Pisa, via Moruzzi 1, 56124 Pisa, Italy;
- Istituto dei Sistemi Complessi del Consiglio Nazionale delle Ricerche (ISC-CNR), sede Sapienza, Pz.le Aldo Moro 5, 00185 Roma, Italy
| | - Ilaria Sanzari
- Zepler Institute for Photonics and Nanoelectronics, Highfield Campus, University of Southampton, Southampton SO17 1BJ, UK; (I.S.); (T.P.)
| | - Franco Dinelli
- Istituto Nazionale di Ottica del Consiglio Nazionale delle Ricerche (INO-CNR), via Moruzzi 1, 56124 Pisa, Italy;
| | - Themistoklis Prodromakis
- Zepler Institute for Photonics and Nanoelectronics, Highfield Campus, University of Southampton, Southampton SO17 1BJ, UK; (I.S.); (T.P.)
| | - Monica Bertoldo
- Istituto per la Sintesi Organica e la Fotoreattivitá del Consiglio Nazionale delle Ricerche (ISOF-CNR), via P. Gobetti 101, 40129 Bologna, Italy
- Dipartimento di Scienze Chimiche e Farmaceutiche, Università degli Studi di Ferrara, via L. Borsari, 45121 Ferrara, Italy
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56
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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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57
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Abstract
Suspensions of soft and highly deformable microgels can be concentrated far more than suspensions of hard colloids, leading to their unusual mechanical properties. Microgels can accommodate compression in suspensions in a variety of ways such as interpenetration, deformation, and shrinking. Previous experiments have offered insightful, but somewhat conflicting, accounts of the behavior of individual microgels in compressed suspensions. We develop a mesoscale computational model to probe the behavior of compressed suspensions consisting of microgels with different architectures at a variety of packing fractions and solvent conditions. We find that microgels predominantly change shape and mildly shrink above random close packing. Interpenetration is only appreciable above space filling, remaining small relative to the mean distance between cross-links. At even higher packing fractions, microgels solely shrink. Remarkably, irrespective of the single-microgel properties, and whether the suspension concentration is changed via changing the particle number density or the swelling state of the particles, which can even result in colloidal gelation, the mechanics of the suspension can be quantified in terms of the single-microgel bulk modulus, which thus emerges as the correct mechanical measure for these type of soft-colloidal suspensions. Our results rationalize the many and varied experimental results, providing insights into the relative importance of effects defining the mechanics of suspensions comprising soft particles.
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58
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Scheffold F. Pathways and challenges towards a complete characterization of microgels. Nat Commun 2020; 11:4315. [PMID: 32887886 PMCID: PMC7473851 DOI: 10.1038/s41467-020-17774-5] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2019] [Accepted: 07/20/2020] [Indexed: 01/07/2023] Open
Abstract
Due to their controlled size, sensitivity to external stimuli, and ease-of-use, microgel colloids are unique building blocks for soft materials made by crosslinking polymers on the micrometer scale. Despite the plethora of work published, many questions about their internal structure, interactions, and phase behavior are still open. The reasons for this lack of understanding are the challenges arising from the small size of the microgel particles, complex pairwise interactions, and their solvent permeability. Here we describe pathways toward a complete understanding of microgel colloids based on recent experimental advances in nanoscale characterization, such as super-resolution microscopy, scattering methods, and modeling.
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Affiliation(s)
- Frank Scheffold
- Department of Physics, University of Fribourg, Chemin du Musée 3, 1700, Fribourg, Switzerland.
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59
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Minato H, Nishizawa Y, Uchihashi T, Suzuki D. Thermoresponsive structural changes of single poly(N-isopropyl acrylamide) hydrogel microspheres under densely packed conditions on a solid substrate. Polym J 2020. [DOI: 10.1038/s41428-020-0372-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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60
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Begam N, Da Vela S, Matsarskaia O, Braun MK, Mariani A, Zhang F, Schreiber F. Packing and dynamics of a protein solution approaching the jammed state. SOFT MATTER 2020; 16:7751-7759. [PMID: 32744265 DOI: 10.1039/d0sm00962h] [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
The packing of proteins and their collective behavior in crowded media is crucial for the understanding of biological processes. Here we study the structural and dynamical evolution of solutions of the globular protein bovine serum albumin with increasing concentration via drying using small angle X-ray scattering and dynamic light scattering. We probe an evolving correlation peak on the scattering profile, corresponding to the inter-protein distance, ξ, which decreases following a power law of the protein volume fraction, φ. The rate of decrease in ξ becomes faster above a protein concentration of ∼200 mg ml-1 (φ = 0.15). The power law exponent changes from 0.33, which is typical of colloidal or protein solutions, to 0.41. During the entire drying process, we observe the development and the growth of two-step relaxation dynamics with increasing φ as revealed by dynamic light scattering. We find three different regimes of the dependence of ξ as a function of φ. In the dilute regime (φ < 0.22), protein molecules are far apart from each other compared to their size. In this case, the dynamics mainly corresponds to Brownian motion. At an intermediate concentration (0.22 < φ < 0.47), inter-protein distances become comparable to the size of protein molecules, leading to a preferential orientation of the ellipsoidal protein molecules along with a possible deformation. In this regime, the dynamics shows two distinct relaxation times. At a very high concentration (φ > 0.47), the system reaches a jammed state. Subsequently, the secondary relaxation time in this state becomes extremely slow. In this state, the protein molecules have approximately one hydration layer. This study contributes to the understanding of protein molecular packing in crowded environments and the phenomenon of density-driven jamming for soft matter systems.
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Affiliation(s)
- Nafisa Begam
- Institut für Angewandte Physik, Universtitat Tübingen, 70276, Tübingen, Germany.
| | - Stefano Da Vela
- Institut für Angewandte Physik, Universtitat Tübingen, 70276, Tübingen, Germany.
| | - Olga Matsarskaia
- Institut für Angewandte Physik, Universtitat Tübingen, 70276, Tübingen, Germany.
| | - Michal K Braun
- Institut für Angewandte Physik, Universtitat Tübingen, 70276, Tübingen, Germany.
| | - Alessandro Mariani
- ESRF-The European Synchrotron, 71 Avenue des Martyrs, 38000, Grenoble, France
| | - Fajun Zhang
- Institut für Angewandte Physik, Universtitat Tübingen, 70276, Tübingen, Germany.
| | - Frank Schreiber
- Institut für Angewandte Physik, Universtitat Tübingen, 70276, Tübingen, Germany.
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61
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Minami S, Watanabe T, Sasaki Y, Minato H, Yamamoto A, Suzuki D, Urayama K. Two-step yielding behavior of densely packed microgel mixtures with chemically dissimilar surfaces and largely different sizes. SOFT MATTER 2020; 16:7400-7413. [PMID: 32699868 DOI: 10.1039/d0sm00366b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Steady-state flow and elastic behavior is investigated for the moderately concentrated binary suspensions of soft microgels (pastes) with chemically dissimilar surfaces, and various degrees of size- and stiffness disparities. The pastes of poly(N-isopropyl acrylamide) (N) and poly(N-isopropyl methacrylamide) (NM) microgels with different values of yield strain γc (γNc > γNMc) are employed as the components. For the single microgel pastes (φ ≈ 1 where φ is apparent volume fraction), the values of γc are governed by the chemical species of constituent polymer in microgel surface whereas γc is insensitive to cross-link density and particle size. We demonstrate that the binary N/NM pastes with large size disparity (RN/NM = DN/DNM < 0.26 where D is the microgel diameter) at low φN (φN: weight fraction of small N microgels) exhibit the peculiarities in several rheological aspects, i.e., the two-step yielding in steady-state flow, and their values of γc and equilibrium shear modulus (G0) being equivalent to those of the single large NM microgel paste. These peculiarities are attributed to the characteristic packing resulting from large size disparity in which all or almost of the small N microgels tend to be accommodated in the gap between the large NM microgels even in moderately concentrated state. This characteristic packing substantially masks the contribution of the small N microgels at low φN, explaining the φN-independent G0 and γc as well as the first yielding governed solely by the large NM microgels. The second yielding results from the emerged contribution of the small N microgels expelled out from the gap by the positional rearrangements after the first yielding. The binary homo-N/N pastes with the similarly large size disparity at low φsmall also exhibit the φsmall-independent values of G0, but they show one-step yielding, indicating that the two-step yielding requires not only sufficiently large size disparity but also chemical dissimilarity (different values of γc) between the two components.
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Affiliation(s)
- Saori Minami
- Department of Macromolecular Science and Engineering, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585, Japan.
| | - Takumi Watanabe
- Graduate School of Textile Science & Technology, Shinshu University, Ueda 386-8567, Japan.
| | - Yuma Sasaki
- Graduate School of Textile Science & Technology, Shinshu University, Ueda 386-8567, Japan.
| | - Haruka Minato
- Graduate School of Textile Science & Technology, Shinshu University, Ueda 386-8567, Japan.
| | - Atsushi Yamamoto
- Department of Macromolecular Science and Engineering, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585, Japan.
| | - Daisuke Suzuki
- Graduate School of Textile Science & Technology, Shinshu University, Ueda 386-8567, Japan. and Research Initiative for Supra-Materials, Interdisciplinary Cluster for Cutting Edge Research, Shinshu University, Ueda 386-8567, Japan
| | - Kenji Urayama
- Department of Macromolecular Science and Engineering, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585, Japan.
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Roullet M, Clegg PS, Frith WJ. Rheology of protein-stabilised emulsion gels envisioned as composite networks 1- Comparison of pure droplet gels and protein gels. J Colloid Interface Sci 2020; 579:878-887. [PMID: 32679385 DOI: 10.1016/j.jcis.2020.05.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 04/30/2020] [Accepted: 05/01/2020] [Indexed: 01/08/2023]
Abstract
HYPOTHESIS Protein-stabilised emulsion gels can be studied in the theoretical framework of colloidal gels, because both protein assemblies and droplets may be considered as soft colloids. These particles differ in their nature, size and softness, and these differences may have an influence on the rheological properties of the gels they form. EXPERIMENTS Pure gels made of milk proteins (sodium caseinate), or of sub-micron protein-stabilised droplets, were prepared by slow acidification of suspensions at various concentrations. Their microstructure was characterised, their viscoelasticity, both in the linear and non-linear regime, and their frequency dependence were measured, and the behaviour of the two types of gels was compared. FINDINGS Protein gels and droplet gels were found to have broadly similar microstructure and rheological properties when compared at fixed volume fraction, a parameter derived from the study of the viscosity of the suspensions formed by proteins and by droplets. The viscoelasticity displayed a power law behaviour in concentration, as did the storage modulus in frequency. Additionally, strain hardening was found to occur at low concentration. These behaviours differed slightly between protein gels and droplet gels, showing that some specific properties of the primary colloidal particles play a role in the development of the rheological properties of the gels.
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Affiliation(s)
- Marion Roullet
- Unilever R&D Colworth, Sharnbrook, Bedford MK44 1LQ, UK; School of Physics and Astronomy, University of Edinburgh, Peter Guthrie Tait Road, Edinburgh EH9 3FD, UK.
| | - Paul S Clegg
- School of Physics and Astronomy, University of Edinburgh, Peter Guthrie Tait Road, Edinburgh EH9 3FD, UK.
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63
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Frenzel L, Lokteva I, Koof M, Narayanan S, Grübel G, Lehmkühler F. Influence of TMAO as co-solvent on the gelation of silica-PNIPAm core-shell nanogels at intermediate volume fractions. Chemphyschem 2020; 21:1318-1325. [PMID: 32250508 PMCID: PMC7318175 DOI: 10.1002/cphc.202000114] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 03/20/2020] [Indexed: 12/29/2022]
Abstract
We study the structure and dynamics of poly(N-isopropylacrylamide) (PNIPAm) core-shell nanogels dispersed in aqueous trimethylamine N-oxide (TMAO) solutions by means of small-angle X-ray scattering and X-ray photon correlation spectroscopy (XPCS). Upon increasing the temperature above the lower critical solution temperature of PNIPAm at 33 °C, a colloidal gel is formed as identified by an increase of I(q) at small q as well as a slowing down of sample dynamics by various orders of magnitude. With increasing TMAO concentration the gelation transition shifts linearly to lower temperatures. Above a TMAO concentration of approximately 0.40 mol/L corresponding to a 1 : 1 ratio of TMAO and NIPAm groups, collapsed PNIPAm states are found for all temperatures without any gelation transition. This suggests that reduction of PNIPAm-water hydrogen bonds due to the presence of TMAO results in a stabilisation of the collapsed PNIPAm state and suppresses gelation of the nanogel.
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Affiliation(s)
- Lara Frenzel
- Deutsches Elektronen-Synchrotron DESYNotkestr. 8522607HamburgGermany
- The Hamburg Centre for Ultrafast ImagingLuruper Chaussee 14922761HamburgGermany
| | - Irina Lokteva
- Deutsches Elektronen-Synchrotron DESYNotkestr. 8522607HamburgGermany
- The Hamburg Centre for Ultrafast ImagingLuruper Chaussee 14922761HamburgGermany
| | - Michael Koof
- Deutsches Elektronen-Synchrotron DESYNotkestr. 8522607HamburgGermany
- The Hamburg Centre for Ultrafast ImagingLuruper Chaussee 14922761HamburgGermany
| | - Suresh Narayanan
- Advanced Photon SourceArgonne National LaboratoryArgonneIllinois60439United States
| | - Gerhard Grübel
- Deutsches Elektronen-Synchrotron DESYNotkestr. 8522607HamburgGermany
- The Hamburg Centre for Ultrafast ImagingLuruper Chaussee 14922761HamburgGermany
| | - Felix Lehmkühler
- Deutsches Elektronen-Synchrotron DESYNotkestr. 8522607HamburgGermany
- The Hamburg Centre for Ultrafast ImagingLuruper Chaussee 14922761HamburgGermany
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64
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Self-templating assembly of soft microparticles into complex tessellations. Nature 2020; 582:219-224. [DOI: 10.1038/s41586-020-2341-6] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Accepted: 03/17/2020] [Indexed: 01/19/2023]
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65
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Pradeep S, Hsiao LC. Contact criterion for suspensions of smooth and rough colloids. SOFT MATTER 2020; 16:4980-4989. [PMID: 32432605 DOI: 10.1039/d0sm00072h] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We report a procedure to obtain the search distance used to determine particle contact in dense suspensions of smooth and rough colloids. This method works by summing physically relevant length scales in an uncertainty analysis and does not require detailed quantification of the surface roughness. We suspend sterically stabilized, fluorescent poly(methyl methacrylate) colloids in a refractive index-matched solvent, squalene, in order to ensure hard sphere-like behavior. High speed centrifugation is used to pack smooth and rough colloids to their respective jamming points, φJ. The jammed suspensions are subsequently diluted with known volumes of solvent to φ < φJ. Structural parameters obtained from confocal laser scanning micrographs of the diluted colloidal suspensions are extrapolated to φJ to determine the mean contact number at jamming, 〈z〉J. Contact below jamming refers to nearest neighbors at a length scale below which the effects of hydrodynamic or geometric friction come into play. Sensitivity analyses show that a deviation of the search distance by 1% of the particle diameter results in 〈z〉 changing by up to 10%, with the error in contact number distribution being magnified in dense suspensions (φ > 0.50) due to an increased number of nearest neighbors in the first coordination shell.
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Affiliation(s)
- Shravan Pradeep
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC 27695, USA.
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66
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Zanatta M, Tavagnacco L, Buratti E, Chiessi E, Natali F, Bertoldo M, Orecchini A, Zaccarelli E. Atomic scale investigation of the volume phase transition in concentrated PNIPAM microgels. J Chem Phys 2020; 152:204904. [PMID: 32486676 DOI: 10.1063/5.0007112] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Combining elastic incoherent neutron scattering and differential scanning calorimetry, we investigate the occurrence of the volume phase transition (VPT) in very concentrated poly-(N-isopropyl-acrylamide) (PNIPAM) microgel suspensions, from a polymer weight fraction of 30 wt. % up to dry conditions. Although samples are arrested at the macroscopic scale, atomic degrees of freedom are equilibrated and can be probed in a reproducible way. A clear signature of the VPT is present as a sharp drop in the mean square displacement of PNIPAM hydrogen atoms obtained by neutron scattering. As a function of concentration, the VPT gets smoother as dry conditions are approached, whereas the VPT temperature shows a minimum at about 43 wt. %. This behavior is qualitatively confirmed by calorimetry measurements. Molecular dynamics simulations are employed to complement experimental results and gain further insights into the nature of the VPT, confirming that it involves the formation of an attractive gel state between the microgels. Overall, these results provide evidence that the VPT in PNIPAM-based systems can be detected at different time- and length-scales as well as under overcrowded conditions.
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Affiliation(s)
- M Zanatta
- Department of Physics, University of Trento, I-38123 Trento, Italy
| | - L Tavagnacco
- CNR-ISC and Department of Physics, Sapienza University of Rome, I-00185 Roma, Italy
| | - E Buratti
- CNR-ISC and Department of Physics, Sapienza University of Rome, I-00185 Roma, Italy
| | - E Chiessi
- Department of Chemical Sciences and Technologies, University of Rome Tor Vergata, I-00133 Roma, Italy
| | - F Natali
- CNR-IOM, Operative Group in Grenoble (OGG), c/o Institut Laue Langevin, F-38042 Grenoble, France
| | - M Bertoldo
- Department of Chemical and Pharmaceutical Sciences, University of Ferrara, I-44121 Ferrara, Italy
| | - A Orecchini
- Department of Physics and Geology, University of Perugia, I-06123 Perugia, Italy
| | - E Zaccarelli
- CNR-ISC and Department of Physics, Sapienza University of Rome, I-00185 Roma, Italy
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67
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Dutta C, Bishop LDC, Zepeda O J, Chatterjee S, Flatebo C, Landes CF. Imaging Switchable Protein Interactions with an Active Porous Polymer Support. J Phys Chem B 2020; 124:4412-4420. [PMID: 32441098 DOI: 10.1021/acs.jpcb.0c01807] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Mechanistic details about how local physicochemistry of porous interfaces drives protein transport mechanisms are necessary to optimize biomaterial applications. Cross-linked hydrogels made of stimuli-responsive polymers have potential for active protein capture and release through tunable steric and chemical transformations. Simultaneous monitoring of dynamic changes in both protein transport and interfacial polymer structure is an experimental challenge. We use single-particle tracking (SPT) and fluorescence correlation spectroscopy Super-resolution Optical Fluctuation Imaging (fcsSOFI) to relate the switchable changes in size and structure of a pH-responsive hydrogel to the interfacial transport properties of a model protein, lysozyme. SPT analysis reveals the reversible switching of protein transport dynamics in and at the hydrogel polymer in response to pH changes. fcsSOFI allows us to relate tunable heterogeneity of the hydrogels and pores to reversible changes in the distribution of confined diffusion and adsorption/desorption. We find that physicochemical heterogeneity of the hydrogels dictates protein confinement and desorption dynamics, particularly at pH conditions in which the hydrogels are swollen.
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Affiliation(s)
- Chayan Dutta
- Department of Chemistry, Rice University, Houston, Texas 77005, United States
| | - Logan D. C. Bishop
- Department of Chemistry, Rice University, Houston, Texas 77005, United States
| | - Jorge Zepeda O
- Department of Electrical and Computer Engineering, Rice University, Houston, Texas 77005, United States
| | - Sudeshna Chatterjee
- Department of Chemistry, Rice University, Houston, Texas 77005, United States
| | - Charlotte Flatebo
- Department of Chemistry, Rice University, Houston, Texas 77005, United States
- Applied Physics Program, Rice University, Houston, Texas 77005, United States
| | - Christy F. Landes
- Department of Chemistry, Rice University, Houston, Texas 77005, United States
- Department of Electrical and Computer Engineering, Rice University, Houston, Texas 77005, United States
- Department of Chemical and Biomolecular Engineering, Rice University, HoustonTexas 77005, United States
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68
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Minami S, Yamamoto A, Oura S, Watanabe T, Suzuki D, Urayama K. Criteria for colloidal gelation of thermo-sensitive poly(N-isopropylacrylamide) based microgels. J Colloid Interface Sci 2020; 568:165-175. [DOI: 10.1016/j.jcis.2020.02.047] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 02/12/2020] [Accepted: 02/13/2020] [Indexed: 11/24/2022]
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69
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Månsson LK, Peng F, Crassous JJ, Schurtenberger P. A microgel-Pickering emulsion route to colloidal molecules with temperature-tunable interaction sites. SOFT MATTER 2020; 16:1908-1921. [PMID: 31995090 DOI: 10.1039/c9sm02401h] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
A simple Pickering emulsion route has been developed for the assembly of temperature-responsive poly(N-isopropylacrylamide) (PNIPAM) microgel particles into colloidal molecules comprising a small number of discrete microgel interaction sites on a central oil emulsion droplet. Here, the surface activity of the microgels serves to drive their assembly through adsorption to growing polydimethylsiloxane (PDMS) emulsion oil droplets of high monodispersity, prepared in situ via ammonia-catalysed hydrolysis and condensation of dimethyldiethoxysilane (DMDES). A dialysis step is employed in order to limit further growth once the target assembly size has been reached, thus yielding narrowly size-distributed, colloidal molecule-like microgel-Pickering emulsion oil droplets with well-defined microgel interaction sites. The temperature-responsiveness of the PNIPAM interaction sites will allow for the directional interactions to be tuned in a facile manner with temperature, all the way from soft repulsive to short-range attractive as the their volume phase transition temperature (VPTT) is crossed. Finally, the microgel-Pickering emulsion approach is extended to a mixture of PNIPAM and poly(N-isopropylmethacrylamide) (PNIPMAM) microgels that differ with respect to their VPTT, this in order to prepare patchy colloidal molecules where the directional interactions will be more readily resolved.
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Affiliation(s)
- Linda K Månsson
- Division of Physical Chemistry, Lund University, POB 124, SE-22100 Lund, Sweden. and NanoLund, POB 118, SE-22100 Lund, Sweden
| | - Feifei Peng
- Division of Physical Chemistry, Lund University, POB 124, SE-22100 Lund, Sweden. and NanoLund, POB 118, SE-22100 Lund, Sweden
| | - Jérôme J Crassous
- Institute of Physical Chemistry, RWTH Aachen University, 52074 AAchen, Germany
| | - Peter Schurtenberger
- Division of Physical Chemistry, Lund University, POB 124, SE-22100 Lund, Sweden. and NanoLund, POB 118, SE-22100 Lund, Sweden and Lund Institute of Advanced Neutron and X-ray Science (LINXS), Scheelevägen 19, SE-22370 Lund, Sweden
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70
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Das A N, Begam N, Chandran S, Swain A, Sprung M, Basu JK. Thermal stability and dynamics of soft nanoparticle membranes: role of entropy, enthalpy and membrane compressibility. SOFT MATTER 2020; 16:1117-1124. [PMID: 31894229 DOI: 10.1039/c9sm01946d] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Nanoparticle based ultra-thin membranes have been shown to have remarkable mechanical properties while also possessing novel electrical, optical or magnetic properties, which could be controlled by tailoring properties at the level of individual nanoparticles. Since in most cases the ultra-thin membranes are coupled to some substrates, the role of membrane-substrate interactions, apart from nanoparticle-nanoparticle interactions become very crucial in understanding their mechanical and thermal stability, as well as their plethora of applications. However, systematic studies in this direction have been conspicuously absent. Here we report thermal stability and the corresponding microscopic dynamics of polymer supported ultra-thin membranes comprising of self-assembled, ordered grains of polymer grafted nanoparticles having tunable mechanical properties. The initially ordered membranes show distinct pathways for temperature induced disordering depending on membrane flexibility as well as on interfacial entropic and enthalpic interactions with the underlying polymer thin film. We also observe contrasting temperature dependence of microscopic dynamics of these membranes depending on whether the graft polymer-substrate polymer interactions are predominantly entropic or enthalpic in nature. Our results suggest that apart from their varied applications, the soft nanoparticle-polymer hybrid membranes are a playground for rich physics involving subtle entropic and enthalpic effects along with the nanoparticles softness, which eventually determine their thermo-mechanical stability.
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Affiliation(s)
- Nimmi Das A
- Department of Physics, Indian Institute of Science, Bangalore, 560012, India.
| | - Nafisa Begam
- Institute of Applied Physics, University of Tuebingen, 72076 Tuebingen, Germany
| | | | - Aparna Swain
- Department of Physics, Indian Institute of Science, Bangalore, 560012, India.
| | - Michael Sprung
- Deutsches Elektronen Synchrotron DESY, Notkestresse 85, 22607 Hamburg, Germany
| | - J K Basu
- Department of Physics, Indian Institute of Science, Bangalore, 560012, India.
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71
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Scotti A, Brugnoni M, G Lopez C, Bochenek S, Crassous JJ, Richtering W. Flow properties reveal the particle-to-polymer transition of ultra-low crosslinked microgels. SOFT MATTER 2020; 16:668-678. [PMID: 31815271 DOI: 10.1039/c9sm01451a] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Exploiting soft, adaptive microgels as building blocks for soft materials with controlled and predictable viscoelastic properties is of great interest for both industry and fundamental research. Here the flow properties of different poly(N-isopropylacrylamide) (pNIPAM) microgels are compared: regularly crosslinked versus ultra-low crosslinked (ULC) microgels. The latter are the softest microgels that can be produced via precipitation polymerization. The viscosity of ULC microgel suspensions at low concentrations can be described with models typically used for hard spheres and regularly crosslinked microgels. In contrast, at higher concentrations, ULC microgels show a much softer behavior compared to regularly crosslinked microgels. The increase of the storage modulus with concentration discloses that while for regularly crosslinked microgels the flow properties are mainly determined by the more crosslinked core, for ULC microgels the brush-like interaction is dominant at high packing fractions. Both the flow curves and the increase of the storage modulus with concentration indicates that ULC microgels can form glass and even reach an apparent jammed state despite their extreme softness. In contrast, the analysis of oscillatory frequency sweep measurements show that when approaching the glass transition the ultra-low crosslinked microgels behave as the regularly crosslinked microgels. This is consistent with a recent study showing that in this concentration range the equilibrium phase behavior of these ULC microgels is the one expected for regularly crosslinked microgels.
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Affiliation(s)
- Andrea Scotti
- Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany.
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72
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Frenzel L, Lehmkühler F, Koof M, Lokteva I, Grübel G. The phase diagram of colloidal silica-PNIPAm core-shell nanogels. SOFT MATTER 2020; 16:466-475. [PMID: 31803889 DOI: 10.1039/c9sm01884k] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We study the structure and dynamics of aqueous dispersions of densely packed core-shell nanoparticles composed of a silica core and a poly(N-isoproylacrylamide) (PNIPAm) shell as a function of temperature and concentration. With small angle X-ray scattering (SAXS) and X-ray photon correlation spectroscopy (XPCS) we shed light on the structural and dynamical changes of the thermo-responsive colloidal nanogel during its volume phase transition at a lower critical solution temperature (LCST) of 32 °C. A transition of the dynamics and its distinct dependency on the particle number concentration could be determined by analysing the intensity autocorrelation function while the structural transition remains concentration independent. We found the dynamics of a jammed system beyond a critical concentration. In addition, by variation of the PNIPAm shell size we tuned both the effective volume fraction and the underlying nature of the dynamics in the system. With our results we can present a full phase diagram of a PNIPAm core-shell system that spans from diluted suspensions, where the system behaves like a liquid, to an effective volume fraction of more than ninety percent where after exceeding a critical concentration the system undergoes a temperature-induced transition from a liquid towards a colloidal gel.
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Affiliation(s)
- Lara Frenzel
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany.
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73
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Mandal BK, Mishra P. Pair correlation function and freezing transitions in a two-dimensional system of model ultrasoft colloids. Mol Phys 2019. [DOI: 10.1080/00268976.2019.1706774] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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74
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Linkhorst J, Rabe J, Hirschwald LT, Kuehne AJC, Wessling M. Direct Observation of Deformation in Microgel Filtration. Sci Rep 2019; 9:18998. [PMID: 31831846 PMCID: PMC6908707 DOI: 10.1038/s41598-019-55516-w] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 11/06/2019] [Indexed: 01/09/2023] Open
Abstract
Colloidal filtration processes using porous membranes suffer from productivity loss due to colloidal matter retention and continuous build-up by the retained matter. Especially during filtration of soft matter, the deformation of the individual colloids that make up the filter cake may be significant; however, this deformation and its impact remain unresolved so far. Yet, understanding the deformation on the single colloid level as well as on the ensemble level is important to be able to deconvolute filter cake properties from resistance increase of the membrane either by simultaneous internal adsorption or blocking of pores. Here, we report on the compression of a filter cake by filtrating soft microgels in a microfluidic channel in front of a model membrane. To study the single colloid deformation amorphous and crystalline domains were built up in front of the membrane and visualized on-line using confocal fluorescence microscopy while adjusting the degree of permeation, i.e., the transmembrane flux. Results show locally pronounced asymmetric deformation in amorphous domains, while the microgels in colloidal crystals approached regular polyeder shape. Increasing the flux beyond the maximum colloid deformation results in non-isochoric microgel behavior. The presented methodology enables a realistic description of complex colloidal matter deposits during filtration.
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Affiliation(s)
- John Linkhorst
- RWTH Aachen University, Chemical Process Engineering, Aachen, 52074, Germany
| | - Jonas Rabe
- RWTH Aachen University, Chemical Process Engineering, Aachen, 52074, Germany
| | - Lukas T Hirschwald
- RWTH Aachen University, Chemical Process Engineering, Aachen, 52074, Germany
| | - Alexander J C Kuehne
- DWI - Leibniz Institute for Interactive Materials, Aachen, 52074, Germany
- Ulm University, OC3 - Institute of Organic and Macromolecular Chemistry, Ulm, 89081, Germany
| | - Matthias Wessling
- RWTH Aachen University, Chemical Process Engineering, Aachen, 52074, Germany.
- DWI - Leibniz Institute for Interactive Materials, Aachen, 52074, Germany.
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75
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Karanastasis AA, Kenath GS, Sundararaman R, Ullal CK. Quantification of functional crosslinker reaction kinetics via super-resolution microscopy of swollen microgels. SOFT MATTER 2019; 15:9336-9342. [PMID: 31687735 DOI: 10.1039/c9sm01618j] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Super resolution microscopy (SRM) brings the advantages of optical microscopy to the imaging of nanostructured soft matter, and in colloidal microgels, promises to quantify variations of crosslink densities at unprecedented length scales. However, the distribution of all crosslinks does not coincide with that of dye-tagged crosslinks, and density quantification in SRM is not guaranteed due to over/under-counting dye molecules. Here we demonstrate that SRM images of microgels encode reaction rate constants of functional cross linkers, which hold the key to correlating these distributions. Combined with evolution of microgel particle radii, the functional cross linker distributions predict consumption versus time with high fidelity. Using a Bayesian regression approach, we extract reaction rate constants for homo and cross propagation of the functional crosslinker, which should be widely useful for predicting spatial variations in crosslink density of gels.
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Affiliation(s)
- Apostolos A Karanastasis
- Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180, USA.
| | - Gopal S Kenath
- Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180, USA.
| | - Ravishankar Sundararaman
- Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180, USA.
| | - Chaitanya K Ullal
- Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180, USA.
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76
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Vialar P, Merzeau P, Giasson S, Drummond C. Compliant Surfaces under Shear: Elastohydrodynamic Lift Force. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:15605-15613. [PMID: 31408351 DOI: 10.1021/acs.langmuir.9b02019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
In this work, we have investigated the behavior under shear and compression of mica surfaces coated with poly(N-isopropylacrylamide) cationic microgels. We have observed the emergence of velocity dependent, shear-induced normal forces, which can be large enough to entrain a fluid film that separates the surfaces out of contact, driving the dynamic system from conditions of boundary to hydrodynamic lubrication. By implementing a feedback-loop control on the surface separation, we were able to quantify the magnitude of the lift force as a function of the surface separation and driving speed. Our results illustrate how elastohydrodynamic effects can play an important role in the lubrication of compliant surfaces, providing pathways for control of friction and wear.
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Affiliation(s)
- Pierre Vialar
- CNRS, Centre de Recherche Paul Pascal (CRPP), UMR 5031 , F-33600 Pessac , France
- Université Bordeaux, CRPP , F-33600 Pessac , France
| | - Pascal Merzeau
- CNRS, Centre de Recherche Paul Pascal (CRPP), UMR 5031 , F-33600 Pessac , France
- Université Bordeaux, CRPP , F-33600 Pessac , France
| | - Suzanne Giasson
- Department of Chemistry and Faculty of Pharmacy , Université de Montréal , C.P. 6128, succursale Centre-Ville , Montréal , QC Canada , H3C 3J7
| | - Carlos Drummond
- CNRS, Centre de Recherche Paul Pascal (CRPP), UMR 5031 , F-33600 Pessac , France
- Université Bordeaux, CRPP , F-33600 Pessac , France
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77
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Purohit A, Centeno SP, Wypysek SK, Richtering W, Wöll D. Microgel PAINT - nanoscopic polarity imaging of adaptive microgels without covalent labelling. Chem Sci 2019; 10:10336-10342. [PMID: 32110321 PMCID: PMC6984396 DOI: 10.1039/c9sc03373d] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Accepted: 09/16/2019] [Indexed: 12/13/2022] Open
Abstract
Polymer nanostructures have enormous potential for various applications in materials and life sciences. In order to exploit and understand their full capabilities, a detailed analysis of their structures and the environmental conditions in them is essential on the nanoscopic scale. With a super-resolution fluorescence microscopy technique known as PAINT (Points Accumulation for Imaging in Nanoscale Topography), we imaged colloidal hydrogel networks, so-called microgels, having a hydrodynamic radius smaller than the diffraction limit, gaining unprecedented insight into their full 3D structure which is not accessible in this much detail with any other experimental method. In addition to imaging of the microgel structure, the use of Nile Red as the solvatochromic fluorophore allowed us to resolve the polarity conditions within the investigated microgels, thus providing nanoscopic information on the x,y,z-position of labels including their polarity without the need of covalent labelling. With this imaging approach, we give a detailed insight into adapting structural and polarity properties of temperature-responsive microgels when changing the temperature beyond the volume phase transition.
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Affiliation(s)
- Ashvini Purohit
- Institute of Physical Chemistry , RWTH Aachen University , Landoltweg 2 , 52074 Aachen , Germany .
| | - Silvia P Centeno
- Institute of Physical Chemistry , RWTH Aachen University , Landoltweg 2 , 52074 Aachen , Germany .
| | - Sarah K Wypysek
- Institute of Physical Chemistry , RWTH Aachen University , Landoltweg 2 , 52074 Aachen , Germany .
| | - Walter Richtering
- Institute of Physical Chemistry , RWTH Aachen University , Landoltweg 2 , 52074 Aachen , Germany .
| | - Dominik Wöll
- Institute of Physical Chemistry , RWTH Aachen University , Landoltweg 2 , 52074 Aachen , Germany .
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78
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Wypysek SK, Scotti A, Alziyadi MO, Potemkin II, Denton AR, Richtering W. Tailoring the Cavity of Hollow Polyelectrolyte Microgels. Macromol Rapid Commun 2019; 41:e1900422. [DOI: 10.1002/marc.201900422] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 10/12/2019] [Indexed: 01/03/2023]
Affiliation(s)
- Sarah K. Wypysek
- Institute of Physical ChemistryRWTH Aachen University 52056 Aachen Germany
| | - Andrea Scotti
- Institute of Physical ChemistryRWTH Aachen University 52056 Aachen Germany
| | | | - Igor I. Potemkin
- Physics DepartmentLomonosov Moscow State University Moscow 119991 Russian Federation
- DWI Leibniz Institute for Interactive Materials 52056 Aachen Germany
- Laboratory of Functional MaterialsNational Research South Ural State University Chelyabinsk 454080 Russian Federation
| | - Alan R. Denton
- Department of PhysicsNorth Dakota State University Fargo ND 58108‐6050 USA
| | - Walter Richtering
- Institute of Physical ChemistryRWTH Aachen UniversityJARA ‐ Soft Matter Science 52056 Aachen Germany
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79
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Månsson LK, de Wild T, Peng F, Holm SH, Tegenfeldt JO, Schurtenberger P. Preparation of colloidal molecules with temperature-tunable interactions from oppositely charged microgel spheres. SOFT MATTER 2019; 15:8512-8524. [PMID: 31633148 DOI: 10.1039/c9sm01779h] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The self-assembly of small colloidal clusters, so-called colloidal molecules, into crystalline materials has proven extremely challenging, the outcome often being glassy, amorphous states where positions and orientations are locked. In this paper, a new type of colloidal molecule is therefore prepared, assembled from poly(N-isopropylacrylamide) (PNIPAM)-based microgels that due to their well documented softness and temperature-response allow for greater defect tolerance compared to hard spheres and for convenient in situ tuning of size, volume fraction and inter-particle interactions with temperature. The microgels (B) are assembled by electrostatic adsorption onto oppositely charged, smaller-sized microgels (A), where the relative size of the two determines the valency (n) of the resulting core-satellite ABn-type colloidal molecules. Following assembly, a microfluidic deterministic lateral displacement (DLD) device is used to effectively isolate AB4-type colloidal molecules of tetrahedral geometry that possess a repulsive-to-attractive transition on crossing the microgels' volume phase transition temperature (VPTT). These soft, temperature-responsive colloidal molecules constitute highly promising building blocks for the preparation of new materials with emergent properties, and their optical wavelength-size makes them especially interesting for optical applications.
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Affiliation(s)
- Linda K Månsson
- Division of Physical Chemistry, Lund University, POB 124, SE-22100 Lund, Sweden. and NanoLund, POB 118, SE-22100 Lund, Sweden
| | - Tym de Wild
- Division of Physical Chemistry, Lund University, POB 124, SE-22100 Lund, Sweden.
| | - Feifei Peng
- Division of Physical Chemistry, Lund University, POB 124, SE-22100 Lund, Sweden. and NanoLund, POB 118, SE-22100 Lund, Sweden
| | - Stefan H Holm
- NanoLund, POB 118, SE-22100 Lund, Sweden and Division of Solid State Physics, Lund University, POB 118, SE-22100 Lund, Sweden
| | - Jonas O Tegenfeldt
- NanoLund, POB 118, SE-22100 Lund, Sweden and Division of Solid State Physics, Lund University, POB 118, SE-22100 Lund, Sweden
| | - Peter Schurtenberger
- Division of Physical Chemistry, Lund University, POB 124, SE-22100 Lund, Sweden. and NanoLund, POB 118, SE-22100 Lund, Sweden and Lund Institute of Advanced Neutron and X-ray Science (LINXS), Scheelevägen 19, SE-22370 Lund, Sweden
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80
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Peng F, Månsson LK, Holm SH, Ghosh S, Carlström G, Crassous JJ, Schurtenberger P, Tegenfeldt JO. A Droplet-Based Microfluidics Route to Temperature-Responsive Colloidal Molecules. J Phys Chem B 2019; 123:9260-9271. [PMID: 31584820 DOI: 10.1021/acs.jpcb.9b07754] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Small clusters of spherical colloids that mimic real molecules, so-called colloidal molecules, hold great promise as building blocks in bottom-up routes to new materials. However, their typical hard sphere nature has hampered their assembly into ordered structures, largely due to a lack of control in the interparticle interactions. To provide easy external control of the interactions, the present work focuses on the preparation of colloidal molecules from temperature-responsive microgel particles that undergo a transition from a soft repulsive to a short-range attractive state as their characteristic volume phase transition temperature (VPTT) is crossed. Preparation of the colloidal molecules starts with the use of a droplet-based microfluidics device to form highly uniform water-in-oil (W/O) emulsion droplets containing, on average and with a narrow distribution, four microgels per droplet. Evaporation of the water then leads to the formation of colloidal molecule-like clusters, which can be harvested following cross-linking and phase transfer. We use a mixture of two types of microgels, one based on poly(N-isopropylacrylamide) (PNIPAM) and the other on poly(N-isopropylmethacrylamide) (PNIPMAM), to prepare bicomponent colloidal molecules, and show that the difference in VPTT between the two allows for induction of attractive interparticle interactions between the PNIPAM interaction sites at temperatures in between the two VPTTs, analogous to the interactions among patchy biomacromolecules such as many proteins.
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Affiliation(s)
| | | | | | | | | | | | - Peter Schurtenberger
- NanoLund , SE-22100 Lund , Sweden.,Lund Institute of advanced Neutron and X-ray Science (LINXS) , Lund University , SE-22370 Lund , Sweden
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81
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Moreno-Guerra JA, Romero-Sánchez IC, Martinez-Borquez A, Tassieri M, Stiakakis E, Laurati M. Model-Free Rheo-AFM Probes the Viscoelasticity of Tunable DNA Soft Colloids. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2019; 15:e1904136. [PMID: 31460707 DOI: 10.1002/smll.201904136] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Indexed: 05/23/2023]
Abstract
Atomic force microscopy rheological measurements (Rheo-AFM) of the linear viscoelastic properties of single, charged colloids having a star-like architecture with a hard core and an extended, deformable double-stranded DNA (dsDNA) corona dispersed in aqueous saline solutions are reported. This is achieved by analyzing indentation and relaxation experiments performed on individual colloidal particles by means of a novel model-free Fourier transform method that allows a direct evaluation of the frequency-dependent linear viscoelastic moduli of the system under investigation. The method provides results that are consistent with those obtained via a conventional fitting procedure of the force-relaxation curves based on a modified Maxwell model. The outcomes show a pronounced softening of the dsDNA colloids, which is described by an exponential decay of both the Young's and the storage modulus as a function of the salt concentration within the dispersing medium. The strong softening is related to a critical reduction of the size of the dsDNA corona, down to ≈70% of its size in a salt-free solution. This can be correlated to significant topological changes of the dense star-like polyelectrolyte forming the corona, which are induced by variations in the density profile of the counterions. Similarly, a significant reduction of the stiffness is obtained by increasing the length of the dsDNA chains, which we attribute to a reduction of the DNA density in the outer region of the corona.
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Affiliation(s)
- José A Moreno-Guerra
- División de Ciencias e Ingenierías, Universidad de Guanajuato, Lomas del Bosque 103, 37150, León, Mexico
| | - Ivany C Romero-Sánchez
- División de Ciencias e Ingenierías, Universidad de Guanajuato, Lomas del Bosque 103, 37150, León, Mexico
| | - Alejandro Martinez-Borquez
- División de Ciencias e Ingenierías, Universidad de Guanajuato, Lomas del Bosque 103, 37150, León, Mexico
| | - Manlio Tassieri
- Division of Biomedical Engineering, School of Engineering, University of Glasgow, Glasgow, G12 8LT, UK
| | - Emmanuel Stiakakis
- Forschungszentrum Jülich, Institute of Complex Systems 3, Leo-Brandt-Strasse, 52425, Jülich, Germany
| | - Marco Laurati
- División de Ciencias e Ingenierías, Universidad de Guanajuato, Lomas del Bosque 103, 37150, León, Mexico
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82
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Experimental synthesis and characterization of rough particles for colloidal and granular rheology. Curr Opin Colloid Interface Sci 2019. [DOI: 10.1016/j.cocis.2019.04.003] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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83
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Minami S, Suzuki D, Urayama K. Rheological aspects of colloidal gels in thermoresponsive microgel suspensions: formation, structure, and linear and nonlinear viscoelasticity. Curr Opin Colloid Interface Sci 2019. [DOI: 10.1016/j.cocis.2019.04.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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84
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Ninarello A, Crassous JJ, Paloli D, Camerin F, Gnan N, Rovigatti L, Schurtenberger P, Zaccarelli E. Modeling Microgels with a Controlled Structure across the Volume Phase Transition. Macromolecules 2019; 52:7584-7592. [PMID: 31656322 PMCID: PMC6812067 DOI: 10.1021/acs.macromol.9b01122] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 08/20/2019] [Indexed: 12/13/2022]
Abstract
![]()
Thermoresponsive microgels are soft
colloids that find widespread
use as model systems for soft matter physics. Their complex internal
architecture, made of a disordered and heterogeneous polymer network,
has been so far a major challenge for computer simulations. In this
work, we put forward a coarse-grained model of microgels whose structural
properties are in quantitative agreement with results obtained with
small-angle X-ray scattering experiments across a wide range of temperatures,
encompassing the volume phase transition. These results bridge the
gap between experiments and simulations of individual microgel particles,
paving the way to theoretically address open questions about their
bulk properties with unprecedented nano- and microscale resolution.
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Affiliation(s)
- Andrea Ninarello
- CNR-ISC Uos Sapienza, Piazzale A. Moro 2, IT-00185 Roma, Italy.,Department of Physics, Sapienza Università di Roma, Piazzale A. Moro 2, IT-00185 Roma, Italy
| | - Jérôme J Crassous
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, DE-52074 Aachen, Germany.,Physical Chemistry, Department of Chemistry, Lund University, Naturvetarvägen 14, SE-22100 Lund, Sweden
| | - Divya Paloli
- Physical Chemistry, Department of Chemistry, Lund University, Naturvetarvägen 14, SE-22100 Lund, Sweden
| | - Fabrizio Camerin
- CNR-ISC Uos Sapienza, Piazzale A. Moro 2, IT-00185 Roma, Italy.,Department of Basic and Applied Sciences for Engineering, Sapienza Università di Roma, via A. Scarpa 14, IT-00161 Roma, Italy
| | - Nicoletta Gnan
- CNR-ISC Uos Sapienza, Piazzale A. Moro 2, IT-00185 Roma, Italy.,Department of Physics, Sapienza Università di Roma, Piazzale A. Moro 2, IT-00185 Roma, Italy
| | - Lorenzo Rovigatti
- Department of Physics, Sapienza Università di Roma, Piazzale A. Moro 2, IT-00185 Roma, Italy.,CNR-ISC Uos Sapienza, Piazzale A. Moro 2, IT-00185 Roma, Italy
| | - Peter Schurtenberger
- Physical Chemistry, Department of Chemistry, Lund University, Naturvetarvägen 14, SE-22100 Lund, Sweden
| | - Emanuela Zaccarelli
- CNR-ISC Uos Sapienza, Piazzale A. Moro 2, IT-00185 Roma, Italy.,Department of Physics, Sapienza Università di Roma, Piazzale A. Moro 2, IT-00185 Roma, Italy
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85
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Frenzel L, Lehmkühler F, Lokteva I, Narayanan S, Sprung M, Grübel G. Anomalous Dynamics of Concentrated Silica-PNIPAm Nanogels. J Phys Chem Lett 2019; 10:5231-5236. [PMID: 31433650 DOI: 10.1021/acs.jpclett.9b01690] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We present the structure and dynamics of highly concentrated core-shell nanoparticles composed of a silica core and a poly(N-isoproylacrylamide) (PNIPAm) shell suspended in water. With X-ray photon correlation spectroscopy, we are able to follow dynamical changes over the volume phase transition of PNIPAm at LCST = 32 °C. On raising the temperature beyond LCST, the structural relaxation times continue to decrease. The effect is accompanied by a transition from stretched to compressed exponential shape of the intensity autocorrelation function. Upon further heating, we find a sudden slowing down for the particles in their collapsed state. The q dependence of the relaxation time shows an anomalous change from τc ∝ q-3 to τc ∝ q-1. Small angle X-ray scattering data evidence a temperature-induced transition from repulsive to attractive forces. Our results indicate a temperature-induced phase transition from a colloidal liquid with polymer-driven dynamics toward a colloidal gel.
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Affiliation(s)
- Lara Frenzel
- Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany
- The Hamburg Centre for Ultrafast Imaging (CUI), Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Felix Lehmkühler
- Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany
- The Hamburg Centre for Ultrafast Imaging (CUI), Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Irina Lokteva
- Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany
- The Hamburg Centre for Ultrafast Imaging (CUI), Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Suresh Narayanan
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Michael Sprung
- Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany
| | - Gerhard Grübel
- Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany
- The Hamburg Centre for Ultrafast Imaging (CUI), Luruper Chaussee 149, 22761 Hamburg, Germany
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86
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Town A, Niezabitowska E, Kavanagh J, Barrow M, Kearns VR, García-Tuñón E, McDonald TO. Understanding the Phase and Morphological Behavior of Dispersions of Synergistic Dual-Stimuli-Responsive Poly( N-isopropylacrylamide) Nanogels. J Phys Chem B 2019; 123:6303-6313. [PMID: 31251624 PMCID: PMC7007235 DOI: 10.1021/acs.jpcb.9b04051] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 06/21/2019] [Indexed: 12/14/2022]
Abstract
This work represents a detailed investigation into the phase and morphological behavior of synergistic dual-stimuli-responsive poly(N-isopropylacrylamide) nanogels, a material that is of considerable interest as a matrix for in situ forming implants. Nanogels were synthesized with four different diameters (65, 160, 310, and 450 nm) as monodispersed particles. These different samples were then prepared and characterized as both dilute (0.1 wt %) and concentrated dispersions (2-22 wt %). In the dilute form, all of the nanogels had the same response to the triggers of the physiological temperature and ionic strength. In water, the nanogels would deswell when heated above 32 °C, while they would aggregate if heated above this temperature at the physiological ionic strength. In the concentrated form, the nanogels exhibited a wide range of morphological changes, with liquid, swollen gel, shrunken gel, and aggregate structures all possible. The occurrence of these structures was dependent on many factors such as the temperature, ionic strength of the solvent, size and ζ-potential of the nanogel, and dispersion concentration. We explored these factors in detail with techniques such as visual studies, rheology, effective volume fraction, and shape factor measurement. The different-sized nanogels displayed differing phase and morphological behavior, but generally higher concentrations of the nanogels (>7 wt %) yielded gels in water with the transitions depending on the temperature. The smallest nanogel (65 nm diameter) exhibited the most unique behavior; it did not form a swollen gel at any concentration tested. Shape factor measurement for the nanogel samples showed that two of the larger three samples (160 and 310 nm) had core-shell structures with denser core cross-linking, while the smallest nanogel sample displayed a homogeneous cross-linked structure. We hypothesize that the smallest nanogels are able to undergo more extensive interpenetration compared to the larger nanogels, which meant that the smallest nanogel was not able to form a swollen gel. In the presence of salt at 12 wt %, all of the nanogels formed aggregates when heated above 35 °C due to the screening of the electrostatic stabilization by the salt. This work revealed unique behavior of the smallest nanogel with a homogeneous cross-linked structure; its phase and morphological behavior were unlike a particle dispersion, rather these were more similar to those of a branched polymer solution. In total, these findings can be used to provide information about the design of poly(N-isopropylacrylamide) nanogel dispersions for different applications where highly specific spatiotemporal control of morphology is required, for example, in the formation of in situ forming implants or for pore blocking behavior.
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Affiliation(s)
- Adam Town
- Department
of Chemistry & Materials Innovation Factory and School of Engineering
& Materials Innovation Factory, University
of Liverpool, Oxford Street, Liverpool L69 7ZD, U.K.
| | - Edyta Niezabitowska
- Department
of Chemistry & Materials Innovation Factory and School of Engineering
& Materials Innovation Factory, University
of Liverpool, Oxford Street, Liverpool L69 7ZD, U.K.
| | - Janine Kavanagh
- Department
of Earth, Ocean and Ecological Sciences, University of Liverpool, Jane Herdman Laboratories, Liverpool L69 3GP, U.K.
| | - Michael Barrow
- Anton
Paar (UK) Ltd., Unit F, The Courtyard, St. Albans AL4 0LA, U.K.
| | - Victoria R. Kearns
- Department
of Eye and Vision Science, University of
Liverpool, Liverpool L7 8TX, U.K.
| | - Esther García-Tuñón
- Department
of Chemistry & Materials Innovation Factory and School of Engineering
& Materials Innovation Factory, University
of Liverpool, Oxford Street, Liverpool L69 7ZD, U.K.
| | - Tom O. McDonald
- Department
of Chemistry & Materials Innovation Factory and School of Engineering
& Materials Innovation Factory, University
of Liverpool, Oxford Street, Liverpool L69 7ZD, U.K.
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87
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Kureha T, Minato H, Suzuki D, Urayama K, Shibayama M. Concentration dependence of the dynamics of microgel suspensions investigated by dynamic light scattering. SOFT MATTER 2019; 15:5390-5399. [PMID: 31204747 DOI: 10.1039/c9sm01030k] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The dynamics of colloidal gel particle suspensions, i.e., microgel suspensions, has been investigated by dynamic light scattering (DLS) over a wide concentration range from the (I) dilute (φ < φcp) to the (II) intermediate (φ ≈ φcp) and (III) high concentration regions (φ ≫ φcp), where φ and φcp are the volume fraction of the gel particles in the suspension and the random close packing fraction, φcp ≈ 0.64, respectively. The time-intensity correlation function exhibited a distinct change with increasing φ, i.e., from ergodic behaviour (region I and II) to nonergodic behaviour (region III). A mode transition from translational (region I) to cooperative diffusion (the so-called gel mode) (region II) was also observed due to the soft and deformable nature of the microgels. Different from the dynamics of hard colloidal glass suspensions, the gel mode remained even at φ ≫ φcp. By using the ensemble-averaged time-correlation function, IE, we quantify the relationship between φ and their dynamics, and show that the soft microgels are deswollen in the densely packed state.
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Affiliation(s)
- Takuma Kureha
- Institute for Solid State Physics, The University of Tokyo, Kashiwa 277-8581, Japan.
| | - Haruka Minato
- Graduate School of Textile Science & Technology, Shinshu University, Ueda 386-8567, Japan
| | - Daisuke Suzuki
- Graduate School of Textile Science & Technology, Shinshu University, Ueda 386-8567, Japan and Division of Smart Textile, Institute for Fiber Engineering, Interdisciplinary Cluster for Cutting Edge Research, Shinshu University, Ueda 386-8567, Japan
| | - Kenji Urayama
- Department of Macromolecular Science and Engineering, Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585, Japan
| | - Mitsuhiro Shibayama
- Institute for Solid State Physics, The University of Tokyo, Kashiwa 277-8581, Japan.
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88
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Rovigatti L, Gnan N, Ninarello A, Zaccarelli E. Connecting Elasticity and Effective Interactions of Neutral Microgels: The Validity of the Hertzian Model. Macromolecules 2019. [DOI: 10.1021/acs.macromol.9b00099] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Lorenzo Rovigatti
- Dipartimento di Fisica, Sapienza Università di Roma, Piazzale A. Moro 2, 00185 Roma, Italy
- CNR-ISC, Uos Sapienza, Piazzale A. Moro 2, 00185 Roma, Italy
| | - Nicoletta Gnan
- Dipartimento di Fisica, Sapienza Università di Roma, Piazzale A. Moro 2, 00185 Roma, Italy
- CNR-ISC, Uos Sapienza, Piazzale A. Moro 2, 00185 Roma, Italy
| | - Andrea Ninarello
- Dipartimento di Fisica, Sapienza Università di Roma, Piazzale A. Moro 2, 00185 Roma, Italy
- CNR-ISC, Uos Sapienza, Piazzale A. Moro 2, 00185 Roma, Italy
| | - Emanuela Zaccarelli
- Dipartimento di Fisica, Sapienza Università di Roma, Piazzale A. Moro 2, 00185 Roma, Italy
- CNR-ISC, Uos Sapienza, Piazzale A. Moro 2, 00185 Roma, Italy
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89
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Conley GM, Zhang C, Aebischer P, Harden JL, Scheffold F. Relationship between rheology and structure of interpenetrating, deforming and compressing microgels. Nat Commun 2019; 10:2436. [PMID: 31164639 PMCID: PMC6547648 DOI: 10.1038/s41467-019-10181-5] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2018] [Accepted: 04/23/2019] [Indexed: 11/30/2022] Open
Abstract
Thermosensitive microgels are widely studied hybrid systems combining properties of polymers and colloidal particles in a unique way. Due to their complex morphology, their interactions and packing, and consequentially the viscoelasticity of suspensions made from microgels, are still not fully understood, in particular under dense packing conditions. Here we study the frequency-dependent linear viscoelastic properties of dense suspensions of micron sized soft particles in conjunction with an analysis of the local particle structure and morphology based on superresolution microscopy. By identifying the dominating mechanisms that control the elastic and dissipative response, we can explain the rheology of these widely studied soft particle assemblies from the onset of elasticity deep into the overpacked regime. Interestingly, our results suggest that the friction between the microgels is reduced due to lubrification mediated by the polymer brush-like corona before the onset of interpenetration.
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Affiliation(s)
- Gaurasundar M Conley
- Department of Physics, University of Fribourg, Chemin du Musée 3, 1700, Fribourg, Switzerland
| | - Chi Zhang
- Department of Physics, University of Fribourg, Chemin du Musée 3, 1700, Fribourg, Switzerland
| | - Philippe Aebischer
- Department of Physics, University of Fribourg, Chemin du Musée 3, 1700, Fribourg, Switzerland
| | - James L Harden
- Department of Physics, University of Ottawa, Ottawa, Ontario, K1N 6N5, Canada
| | - Frank Scheffold
- Department of Physics, University of Fribourg, Chemin du Musée 3, 1700, Fribourg, Switzerland.
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90
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Honda K, Sazuka Y, Iizuka K, Matsui S, Uchihashi T, Kureha T, Shibayama M, Watanabe T, Suzuki D. Hydrogel Microellipsoids that Form Robust String-Like Assemblies at the Air/Water Interface. Angew Chem Int Ed Engl 2019; 58:7294-7298. [PMID: 30957363 DOI: 10.1002/anie.201901611] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Revised: 03/17/2019] [Indexed: 11/09/2022]
Abstract
Soft colloidal particles such as hydrogel microspheres assemble at air/water or oil/water interfaces, where the soft colloids are highly deformed and their surface polymer chains are highly entangled with each other. Herein, we report the formation of robust one-dimensional, string-like colloidal assemblies through self-organization of hydrogel microspheres with shape anisotropy at the air/water interface of sessile droplets. Shape-anisotropic hydrogel microspheres were synthesized via two-step polymerization, whereby a hydrogel shell was formed onto preformed rigid microellipsoids. The shape anisotropy of the hydrogel microspheres was confirmed by transmission electron microscopy and high-speed atomic force microscopy as well as by light-scattering measurements. The present findings are crucial for the understanding of natural self-organization phenomena, where "softness" influences microscopic assembled structures such as those of Nostoc bacteria.
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Affiliation(s)
- Kenshiro Honda
- Graduate School of Textile Science & Technology, Shinshu University, 3-15-1 Tokida Ueda, Nagano, 386-8567, Japan
| | - Yuka Sazuka
- Graduate School of Textile Science & Technology, Shinshu University, 3-15-1 Tokida Ueda, Nagano, 386-8567, Japan
| | - Kojiro Iizuka
- College of Systems Engineering and Science, Shibaura Institute of Technology, 307 Fukasaku, Minuma-ku, Saitama city, Saitama, 337-8570, Japan
| | - Shusuke Matsui
- Graduate School of Textile Science & Technology, Shinshu University, 3-15-1 Tokida Ueda, Nagano, 386-8567, Japan
| | - Takayuki Uchihashi
- Department of Physics and Structural Biology Research Center, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8602, Japan.,Exploratory Research Center on Life and Living Systems, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi, 444-8787, Japan
| | - Takuma Kureha
- Institute for Solid State Physics, The University of Tokyo, Kashiwanoha, Kashiwa, 277-8581, Japan
| | - Mitsuhiro Shibayama
- Institute for Solid State Physics, The University of Tokyo, Kashiwanoha, Kashiwa, 277-8581, Japan
| | - Takumi Watanabe
- Graduate School of Textile Science & Technology, Shinshu University, 3-15-1 Tokida Ueda, Nagano, 386-8567, Japan
| | - Daisuke Suzuki
- Graduate School of Textile Science & Technology, Shinshu University, 3-15-1 Tokida Ueda, Nagano, 386-8567, Japan.,Division of Smart Textiles, Institute for Fiber Engineering, Interdisciplinary Cluster for Cutting Edge Research, Shinshu University, 3-15-1 Tokida Ueda, Nagano, 386-8567, Japan
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91
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Scotti A, Denton AR, Brugnoni M, Houston JE, Schweins R, Potemkin II, Richtering W. Deswelling of Microgels in Crowded Suspensions Depends on Cross-Link Density and Architecture. Macromolecules 2019. [DOI: 10.1021/acs.macromol.9b00729] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Andrea Scotti
- Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany
| | - Alan R. Denton
- Department of Physics, North Dakota State University, Fargo, North Dakota 58108-6050 United States
| | - Monia Brugnoni
- Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany
| | - Judith E. Houston
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich GmbH, Lichtenbergstr. 1, 85748 Garching, Germany
- European Spallation
Source ERIC, Box 176, SE-221 00 Lund, Sweden
| | - Ralf Schweins
- Institut Laue-Langevin
ILL DS/LSS, 71 Avenue des Martyrs, F-38000 Grenoble, France
| | - Igor I. Potemkin
- Physics Department, Lomonosov Moscow State University, 119991 Moscow, Russian Federation
- DWI - Leibniz
Institute
for Interactive Materials, Aachen 52056, Germany
- National Research South
Ural State University, Chelyabinsk 454080, Russian Federation
| | - Walter Richtering
- Institute of Physical Chemistry, RWTH Aachen University, 52056 Aachen, Germany
- JARA, Jülich Aachen
Research Alliance, 52056 Aachen, Germany
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92
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Nishizawa Y, Matsui S, Urayama K, Kureha T, Shibayama M, Uchihashi T, Suzuki D. Non‐Thermoresponsive Decanano‐sized Domains in Thermoresponsive Hydrogel Microspheres Revealed by Temperature‐Controlled High‐Speed Atomic Force Microscopy. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201903483] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Yuichiro Nishizawa
- Graduate School of Textile Science & Technology Shinshu University 3-15-1 Tokida Ueda Nagano 386-8567 Japan
| | - Shusuke Matsui
- Graduate School of Textile Science & Technology Shinshu University 3-15-1 Tokida Ueda Nagano 386-8567 Japan
| | - Kenji Urayama
- Department of Macromolecular Science and Engineering Kyoto Institute of Technology Sakyo-ku Kyoto 606-8585 Japan
| | - Takuma Kureha
- Institute for Solid State PhysicsThe University of Tokyo Kashiwanoha Kashiwa 277-8581 Japan
| | - Mitsuhiro Shibayama
- Institute for Solid State PhysicsThe University of Tokyo Kashiwanoha Kashiwa 277-8581 Japan
| | - Takayuki Uchihashi
- Department of Physics and Structural Biology Research CenterGraduate School of ScienceNagoya University Furo-cho, Chikusa-ku Nagoya Aichi 464-8602 Japan
- Exploratory Research Center on Life and Living Systems National Institutes of Natural Sciences 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
- Division of Smart TextilesInstitute for Fiber EngineeringInterdisciplinary Cluster for Cutting Edge ResearchShinshu University 3-15-1 Tokida Ueda Nagano 386-8567 Japan
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93
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Nishizawa Y, Matsui S, Urayama K, Kureha T, Shibayama M, Uchihashi T, Suzuki D. Non-Thermoresponsive Decanano-sized Domains in Thermoresponsive Hydrogel Microspheres Revealed by Temperature-Controlled High-Speed Atomic Force Microscopy. Angew Chem Int Ed Engl 2019; 58:8809-8813. [PMID: 31056848 DOI: 10.1002/anie.201903483] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Indexed: 11/10/2022]
Abstract
Despite the tremendous efforts devoted to the structural analysis of hydrogel microspheres (microgels), many details of their structures remain unclear. Reported in this study is that thermoresponsive poly(N-isopropyl acrylamide) (pNIPAm)-based microgels exhibit not only the widely accepted core-shell structures, but also inhomogeneous decanano-sized non-thermoresponsive spherical domains within their dense cores, which was revealed by temperature-controlled high-speed atomic force microscopy (TC-HS-AFM). Based on a series of experiments, it is concluded that the non-thermoresponsive domains are characteristic for pNIPAm microgels synthesized by precipitation polymerization, and plausible structures for microgels prepared by other polymerization techniques are proposed.
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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
| | - Shusuke Matsui
- Graduate School of Textile Science & Technology Shinshu University, 3-15-1 Tokida Ueda, Nagano, 386-8567, Japan
| | - Kenji Urayama
- Department of Macromolecular Science and Engineering Kyoto Institute of Technology, Sakyo-ku, Kyoto, 606-8585, Japan
| | - Takuma Kureha
- Institute for Solid State Physics, The University of Tokyo, Kashiwanoha, Kashiwa, 277-8581, Japan
| | - Mitsuhiro Shibayama
- Institute for Solid State Physics, The University of Tokyo, Kashiwanoha, Kashiwa, 277-8581, Japan
| | - Takayuki Uchihashi
- Department of Physics and Structural Biology Research Center, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8602, Japan.,Exploratory Research Center on Life and Living Systems National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi, 444-8787, Japan
| | - Daisuke Suzuki
- Graduate School of Textile Science & Technology Shinshu University, 3-15-1 Tokida Ueda, Nagano, 386-8567, Japan.,Division of Smart Textiles, Institute for Fiber Engineering, Interdisciplinary Cluster for Cutting Edge Research, Shinshu University, 3-15-1 Tokida Ueda, Nagano, 386-8567, Japan
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94
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Karg M, Pich A, Hellweg T, Hoare T, Lyon LA, Crassous JJ, Suzuki D, Gumerov RA, Schneider S, Potemkin II, Richtering W. Nanogels and Microgels: From Model Colloids to Applications, Recent Developments, and Future Trends. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:6231-6255. [PMID: 30998365 DOI: 10.1021/acs.langmuir.8b04304] [Citation(s) in RCA: 310] [Impact Index Per Article: 62.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Nanogels and microgels are soft, deformable, and penetrable objects with an internal gel-like structure that is swollen by the dispersing solvent. Their softness and the potential to respond to external stimuli like temperature, pressure, pH, ionic strength, and different analytes make them interesting as soft model systems in fundamental research as well as for a broad range of applications, in particular in the field of biological applications. Recent tremendous developments in their synthesis open access to systems with complex architectures and compositions allowing for tailoring microgels with specific properties. At the same time state-of-the-art theoretical and simulation approaches offer deeper understanding of the behavior and structure of nano- and microgels under external influences and confinement at interfaces or at high volume fractions. Developments in the experimental analysis of nano- and microgels have become particularly important for structural investigations covering a broad range of length scales relevant to the internal structure, the overall size and shape, and interparticle interactions in concentrated samples. Here we provide an overview of the state-of-the-art, recent developments as well as emerging trends in the field of nano- and microgels. The following aspects build the focus of our discussion: tailoring (multi)functionality through synthesis; the role in biological and biomedical applications; the structure and properties as a model system, e.g., for densely packed arrangements in bulk and at interfaces; as well as the theory and computer simulation.
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Affiliation(s)
- Matthias Karg
- Physical Chemistry I , Heinrich-Heine-University Duesseldorf , 40204 Duesseldorf , Germany
| | - Andrij Pich
- DWI-Leibnitz-Institute for Interactive Materials e.V. , 52056 Aachen , Germany
- Functional and Interactive Polymers, Institute for Technical and Macromolecular Chemistry , RWTH Aachen University , 52056 Aachen , Germany
| | - Thomas Hellweg
- Physical and Biophysical Chemistry , Bielefeld University , 33615 Bielefeld , Germany
| | - Todd Hoare
- Department of Chemical Engineering , McMaster University , Hamilton , Ontario L8S 4L8 , Canada
| | - L Andrew Lyon
- Schmid College of Science and Technology , Chapman University , Orange , California 92866 , United States
| | - J J Crassous
- Institute of Physical Chemistry , RWTH Aachen University , 52056 Aachen , Germany
| | | | - Rustam A Gumerov
- DWI-Leibnitz-Institute for Interactive Materials e.V. , 52056 Aachen , Germany
- Physics Department , Lomonosov Moscow State University , Moscow 119991 , Russian Federation
| | - Stefanie Schneider
- Institute of Physical Chemistry , RWTH Aachen University , 52056 Aachen , Germany
| | - Igor I Potemkin
- DWI-Leibnitz-Institute for Interactive Materials e.V. , 52056 Aachen , Germany
- Physics Department , Lomonosov Moscow State University , Moscow 119991 , Russian Federation
- National Research South Ural State University , Chelyabinsk 454080 , Russian Federation
| | - Walter Richtering
- Institute of Physical Chemistry , RWTH Aachen University , 52056 Aachen , Germany
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95
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Honda K, Sazuka Y, Iizuka K, Matsui S, Uchihashi T, Kureha T, Shibayama M, Watanabe T, Suzuki D. Hydrogel Microellipsoids that Form Robust String‐Like Assemblies at the Air/Water Interface. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201901611] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Kenshiro Honda
- Graduate School of Textile Science & TechnologyShinshu University 3-15-1 Tokida Ueda Nagano 386-8567 Japan
| | - Yuka Sazuka
- Graduate School of Textile Science & TechnologyShinshu University 3-15-1 Tokida Ueda Nagano 386-8567 Japan
| | - Kojiro Iizuka
- College of Systems Engineering and ScienceShibaura Institute of Technology 307 Fukasaku, Minuma-ku Saitama city Saitama 337-8570 Japan
| | - Shusuke Matsui
- Graduate School of Textile Science & TechnologyShinshu University 3-15-1 Tokida Ueda Nagano 386-8567 Japan
| | - Takayuki Uchihashi
- Department of Physics and Structural Biology Research CenterGraduate School of ScienceNagoya University Furo-cho, Chikusa-ku Nagoya Aichi 464-8602 Japan
- Exploratory Research Center on Life and Living SystemsNational Institutes of Natural Sciences 5-1 Higashiyama, Myodaiji Okazaki Aichi 444-8787 Japan
| | - Takuma Kureha
- Institute for Solid State PhysicsThe University of Tokyo Kashiwanoha Kashiwa 277-8581 Japan
| | - Mitsuhiro Shibayama
- Institute for Solid State PhysicsThe University of Tokyo Kashiwanoha Kashiwa 277-8581 Japan
| | - Takumi Watanabe
- Graduate School of Textile Science & TechnologyShinshu University 3-15-1 Tokida Ueda Nagano 386-8567 Japan
| | - Daisuke Suzuki
- Graduate School of Textile Science & TechnologyShinshu University 3-15-1 Tokida Ueda Nagano 386-8567 Japan
- Division of Smart TextilesInstitute for Fiber EngineeringInterdisciplinary Cluster for Cutting Edge ResearchShinshu University 3-15-1 Tokida Ueda Nagano 386-8567 Japan
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96
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Camerin F, Fernández-Rodríguez MÁ, Rovigatti L, Antonopoulou MN, Gnan N, Ninarello A, Isa L, Zaccarelli E. Microgels Adsorbed at Liquid-Liquid Interfaces: A Joint Numerical and Experimental Study. ACS NANO 2019; 13:4548-4559. [PMID: 30865829 DOI: 10.1021/acsnano.9b00390] [Citation(s) in RCA: 73] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Soft particles display highly versatile properties with respect to hard colloids and even more so at fluid-fluid interfaces. In particular, microgels, consisting of a cross-linked polymer network, are able to deform and flatten upon adsorption at the interface due to the balance between surface tension and internal elasticity. Despite the existence of experimental results, a detailed theoretical understanding of this phenomenon is still lacking due to the absence of appropriate microscopic models. In this work, we propose an advanced modeling of microgels at a flat water/oil interface. The model builds on a realistic description of the internal polymeric architecture and single-particle properties of the microgel and is able to reproduce its experimentally observed shape at the interface. Complementing molecular dynamics simulations with in situ cryo-electron microscopy experiments and atomic force microscopy imaging after Langmuir-Blodgett deposition, we compare the morphology of the microgels for different values of the cross-linking ratios. Our model allows for a systematic microscopic investigation of soft particles at fluid interfaces, which is essential to develop predictive power for the use of microgels in a broad range of applications, including the stabilization of smart emulsions and the versatile patterning of surfaces.
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Affiliation(s)
- Fabrizio Camerin
- CNR Institute for Complex Systems, Uos Sapienza , Piazzale Aldo Moro 2 , 00185 Roma , Italy
- Department of Basic and Applied Sciences for Engineering , Sapienza University of Rome , Via Antonio Scarpa 14 , 00161 Roma , Italy
| | - Miguel Ángel Fernández-Rodríguez
- Laboratory for Interfaces, Soft Matter and Assembly, Department of Materials , ETH Zürich , Vladimir-Prelog-Weg 5 , 8093 Zürich , Switzerland
| | - Lorenzo Rovigatti
- CNR Institute for Complex Systems, Uos Sapienza , Piazzale Aldo Moro 2 , 00185 Roma , Italy
- Department of Physics , Sapienza University of Rome , Piazzale Aldo Moro 2 , 00185 Roma , Italy
| | - Maria-Nefeli Antonopoulou
- Laboratory for Interfaces, Soft Matter and Assembly, Department of Materials , ETH Zürich , Vladimir-Prelog-Weg 5 , 8093 Zürich , Switzerland
| | - Nicoletta Gnan
- CNR Institute for Complex Systems, Uos Sapienza , Piazzale Aldo Moro 2 , 00185 Roma , Italy
- Department of Physics , Sapienza University of Rome , Piazzale Aldo Moro 2 , 00185 Roma , Italy
| | - Andrea Ninarello
- CNR Institute for Complex Systems, Uos Sapienza , Piazzale Aldo Moro 2 , 00185 Roma , Italy
- Department of Physics , Sapienza University of Rome , Piazzale Aldo Moro 2 , 00185 Roma , Italy
| | - Lucio Isa
- Laboratory for Interfaces, Soft Matter and Assembly, Department of Materials , ETH Zürich , Vladimir-Prelog-Weg 5 , 8093 Zürich , Switzerland
| | - Emanuela Zaccarelli
- CNR Institute for Complex Systems, Uos Sapienza , Piazzale Aldo Moro 2 , 00185 Roma , Italy
- Department of Physics , Sapienza University of Rome , Piazzale Aldo Moro 2 , 00185 Roma , Italy
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97
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Chaudhary G, Ghosh A, Bharadwaj NA, Kang JG, Braun PV, Schweizer KS, Ewoldt RH. Thermoresponsive Stiffening with Microgel Particles in a Semiflexible Fibrin Network. Macromolecules 2019. [DOI: 10.1021/acs.macromol.9b00124] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
| | | | | | - Jin Gu Kang
- Nanophotonics Research Center, Korea Institute of Science and Technology, Seoul 02792, South Korea
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98
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Responsive hydrogel colloids: Structure, interactions, phase behavior, and equilibrium and nonequilibrium transitions of microgel dispersions. Curr Opin Colloid Interface Sci 2019. [DOI: 10.1016/j.cocis.2019.02.005] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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99
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Li Q, Peng X, McKenna GB. Physical aging and compressed exponential behaviors in a model soft colloidal system. SOFT MATTER 2019; 15:2336-2347. [PMID: 30758036 DOI: 10.1039/c8sm02042f] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Diffusing wave spectroscopy (DWS)-based micro-rheology has been used in different optical geometries (backscattering and transmission) as well as different sample thicknesses in order to probe system dynamics at different length scales [D. J. Pine, D. A. Weitz, J. X. Zhu, E. Herbolzheimer. J. Phys., 1990, 51(18), 2101-2127]. Previous study from this lab [Q. Li, X. Peng, G. B. McKenna. Soft Matter, 2017, 13(7), 1396-1404] indicates the DWS-based micro-rheology observes the system non-equilibrium behaviors differently from macro-rheology. The object of the present work was to further explore the non-equilibrium dynamics and to address the range of utility of DWS as a micro-rheological method. A thermo-sensitive core-shell colloidal system was investigated both during aging and subsequent to aging into a metastable equilibrium state using temperature-jump induced volume fraction-jump experiments. We find that in the non-equilibrium state, significant differences in the measured dynamics are observed for the different geometries and length scales. Compressed exponential relaxations for the autocorrelation function g2(t) were observed for large length scales. However, upon converting the g2(t) data to the mean square displacement (MSD), such differences with length scale diminished and the long-time MSD behavior was consistent with diffusive behavior. These observations in the non-equilibrium behaviors for different length scales leads to questioning of some interpretations in the current field of light scattering-based micro-rheology and provides a possibility to interrogate the aging mechanisms in colloidal glasses from a broader perspective than normally considered in measurements of g2(t) using DWS-based micro-rheology.
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Affiliation(s)
- Qi Li
- Department of Chemical Engineering, Texas Tech University, Lubbock, TX 79409, USA.
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100
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Rovigatti L, Gnan N, Tavagnacco L, Moreno AJ, Zaccarelli E. Numerical modelling of non-ionic microgels: an overview. SOFT MATTER 2019; 15:1108-1119. [PMID: 30543246 PMCID: PMC6371763 DOI: 10.1039/c8sm02089b] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Accepted: 11/26/2018] [Indexed: 05/03/2023]
Abstract
Microgels are complex macromolecules. These colloid-sized polymer networks possess internal degrees of freedom and, depending on the polymer(s) they are made of, can acquire a responsiveness to variations of the environment (temperature, pH, salt concentration, etc.). Besides being valuable for many practical applications, microgels are also extremely important to tackle fundamental physics problems. As a result, these last years have seen a rapid development of protocols for the synthesis of microgels, and more and more research has been devoted to the investigation of their bulk properties. However, from a numerical standpoint the picture is more fragmented, as the inherently multi-scale nature of microgels, whose bulk behaviour crucially depends on the microscopic details, cannot be handled at a single level of coarse-graining. Here we present an overview of the methods and models that have been proposed to describe non-ionic microgels at different length-scales, from the atomistic to the single-particle level. We especially focus on monomer-resolved models, as these have the right level of details to capture the most important properties of microgels, responsiveness and softness. We suggest that these microscopic descriptions, if realistic enough, can be employed as starting points to develop the more coarse-grained representations required to investigate the behaviour of bulk suspensions.
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Affiliation(s)
- Lorenzo Rovigatti
- Dipartimento di Fisica
, Sapienza Università di Roma
,
Piazzale A. Moro 2
, 00185 Roma
, Italy
.
- CNR-ISC
, Uos Sapienza
,
Piazzale A. Moro 2
, 00185 Roma
, Italy
.
| | - Nicoletta Gnan
- Dipartimento di Fisica
, Sapienza Università di Roma
,
Piazzale A. Moro 2
, 00185 Roma
, Italy
.
- CNR-ISC
, Uos Sapienza
,
Piazzale A. Moro 2
, 00185 Roma
, Italy
.
| | - Letizia Tavagnacco
- Dipartimento di Fisica
, Sapienza Università di Roma
,
Piazzale A. Moro 2
, 00185 Roma
, Italy
.
- CNR-ISC
, Uos Sapienza
,
Piazzale A. Moro 2
, 00185 Roma
, Italy
.
| | - Angel J. Moreno
- Centro de Física de Materiales (CSIC, UPV/EHU) and Materials Physics Center MPC
,
Paseo Manuel de Lardizabal 5
, 20018 San Sebastián
, Spain
- Donostia International Physics Center
,
Paseo Manuel de Lardizabal 4
, 20018 San Sebastian
, Spain
| | - Emanuela Zaccarelli
- Dipartimento di Fisica
, Sapienza Università di Roma
,
Piazzale A. Moro 2
, 00185 Roma
, Italy
.
- CNR-ISC
, Uos Sapienza
,
Piazzale A. Moro 2
, 00185 Roma
, Italy
.
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