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Cho NH, Zhang Q, Dufresne EM, Narayanan S, Richards JJ. Microscopic Dynamics of Inverse Wormlike Micelles Probed Using X-ray Photon Correlation Spectroscopy. ACS Macro Lett 2022; 11:575-579. [PMID: 35575339 DOI: 10.1021/acsmacrolett.1c00651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Wormlike micelles (WLMs) are ubiquitous viscoelastic modifiers that share properties with polymer solutions. While their macroscopic rheology is well-understood, their microscopic dynamics remain difficult to measure because they span a large range of time and length scales. In this work, we demonstrate the use of X-ray photon correlation spectroscopy to interrogate the segmental dynamics of inverse WLM solutions swollen with a rubidium chloride solution. We observe a diffusive scaling of the dynamics and extract a temperature-dependent diffusion coefficient, which we associate with the thermal interactions of the slow segmental dynamics near entanglement points. We probe this relaxation process across the unbranched to branched topological transition and find no microstructural evidence of branch formation in the slow mode. Instead, we observe that the dynamics become more homogeneous and prominent as the temperature is reduced and water content increases.
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Affiliation(s)
- Noah H. Cho
- Department of Chemical & Biological Engineering, Northwestern University, Evanston, Illinois 60208, United States
| | - Qingteng Zhang
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Eric M. Dufresne
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Suresh Narayanan
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Jeffrey J. Richards
- Department of Chemical & Biological Engineering, Northwestern University, Evanston, Illinois 60208, United States
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2
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Nigro V, Ruzicka B, Ruta B, Zontone F, Bertoldo M, Buratti E, Angelini R. Relaxation Dynamics, Softness, and Fragility of Microgels with Interpenetrated Polymer Networks. Macromolecules 2020. [DOI: 10.1021/acs.macromol.9b01560] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Valentina Nigro
- Istituto dei Sistemi Complessi del Consiglio Nazionale delle Ricerche (ISC-CNR), sede Sapienza, Pz.le Aldo Moro 5, I-00185 Roma, Italy
- Dipartimento di Fisica, Sapienza Università di Roma, I-00185 Roma, Italy
| | - Barbara Ruzicka
- Istituto dei Sistemi Complessi del Consiglio Nazionale delle Ricerche (ISC-CNR), sede Sapienza, Pz.le Aldo Moro 5, I-00185 Roma, Italy
- Dipartimento di Fisica, Sapienza Università di Roma, I-00185 Roma, Italy
| | - Beatrice Ruta
- France Univ Lyon, Universitè Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, 69100 Villeurbanne, France
- ESRF The European Synchrotron, CS40220, 38043 Grenoble Cedex 9, France
| | - Federico Zontone
- ESRF The European Synchrotron, CS40220, 38043 Grenoble Cedex 9, France
| | - Monica Bertoldo
- Istituto per la Sintesi Organica e la Fotoreattività del Consiglio Nazionale delle Ricerche (ISOF-CNR), via P. Gobetti
101, 40129 Bologna, Italy
| | - Elena Buratti
- Istituto dei Sistemi Complessi del Consiglio Nazionale delle Ricerche (ISC-CNR), sede Sapienza, Pz.le Aldo Moro 5, I-00185 Roma, Italy
| | - Roberta Angelini
- Istituto dei Sistemi Complessi del Consiglio Nazionale delle Ricerche (ISC-CNR), sede Sapienza, Pz.le Aldo Moro 5, I-00185 Roma, Italy
- Dipartimento di Fisica, Sapienza Università di Roma, I-00185 Roma, Italy
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3
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Viscoelastic effects on dynamics of concentration fluctuations in semi-dilute polymer solution in the good solvent regime. POLYMER 2019. [DOI: 10.1016/j.polymer.2019.121622] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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4
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Koziol M, Fischer K, Seiffert S. Origin of the low-frequency plateau and the light-scattering slow mode in semidilute poly(ethylene glycol) solutions. SOFT MATTER 2019; 15:2666-2676. [PMID: 30839030 DOI: 10.1039/c8sm02263a] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
A low-frequency plateau is often found in the rheological spectra of various kinds of semidilute solutions of polymers and other colloids; also, many such solutions have been reported to show slow-modes in their dynamic light scattering autocorrelation functions. Both these observations may lead to the hypothesis of weak associative network structures built by the dissolved polymer chains or colloidal building blocks. To challenge this hypothesis, we conduct a series of comparative studies on semidilute solutions of poly(ethylene glycol) by using classical rheology as well as passive microrheology based on dynamic light scattering, along with structural studies using static light scattering. Although we indeed find a low-frequency plateau using classical shear rheology, even at elevated temperatures where potential polymer aggregates should be broken, no such plateau is observed in any of our microrheology experiments. Also, dynamic and static light scattering studies on the polymer solutions do not confirm the presence of larger structural entities: no slow mode can be detected in the autocorrelation function of the scattering intensity signal, and this signal is angle independent if the samples are purified by a thorough procedure of filtration. Based on these findings, we conclude that the low-frequency plateau in classical rheology results is an instrument effect caused by erroneous recording of the phase angle, although the magnitude of the torque lies well within the resolution of the rheometer. We also conclude that slow modes in dynamic light scattering on solutions of poly(ethylene glycol) are impurity-based artifacts rather than due to actual associated structures.
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Affiliation(s)
- Martha Koziol
- Johannes Gutenberg-Universität Mainz, Institute of Physical Chemistry, Duesbergweg 10-14, D-55128 Mainz, Germany.
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Yi HL, Hua CC. Peculiar Aggregation Features in Poly(3-hexylthiophene)/Chlorobenzene Solutions. Macromolecules 2018. [DOI: 10.1021/acs.macromol.8b02619] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Han-Liou Yi
- Department of Chemical Engineering, National Chung Cheng University, Chiayi 62102, Taiwan
| | - Chi-Chung Hua
- Department of Chemical Engineering, National Chung Cheng University, Chiayi 62102, Taiwan
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6
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Garate H, Li KW, Bouyer D, Guenoun P. Optical tracking of relaxation dynamics in semi-dilute hydroxypropylcellulose solutions as a precise phase transition probe. SOFT MATTER 2017; 13:7161-7171. [PMID: 28902225 DOI: 10.1039/c7sm01501a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Phase separation of thermo-responsive polymers in solution is a complex process, whose understanding is essential to screen and design materials with diverse technological applications. Here we report on a method based on dynamic light scattering (DLS) experiments to investigate the phase separation of thermo-responsive polymer solutions and precisely define the transition temperature (TPS). Our results are applied on hydroxypropylcellulose (HPC) solutions as an important biosourced green water-soluble polymer. As determined by DLS, the amplitudes of the fast and slow modes of relaxation dynamics evolve as temperature gets closer to the phase transition point eventually leading to phase separation. The evolution of relaxation modes with temperature is markedly different for concentrations below the overlap concentration (c*) (dilute regime), above c* (semi-dilute regime) and above the entanglement concentration (ce). In the three cases though, the fast and slow mode amplitudes undergo a sharp transition in a narrow temperature range, defining accurately the phase separation locus. The results agree with turbidimetric analysis for the phase transition determination but with a better precision. Our results also show that the one-phase dynamics and phase separation dynamics in the two-phase region are only in continuity for c > ce, revealing mechanistic details about the HPC phase separation process. Above TPS we identify a temperature range where the intensity autocorrelation function has a single-exponential shape. In the latter regime, we monitor the growth kinetics of polymer domains and provide clues to rationalize the stabilizing effects of the interfaces leading to the arrested-like phase separation behavior observed for HPC.
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Affiliation(s)
- Hernan Garate
- LIONS, NIMBE, CEA, CNRS, Université Paris-Saclay, CEA-Saclay, 91191 CEDEX Gif-sur-Yvette, France.
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Fabrication of injectable high strength hydrogel based on 4-arm star PEG for cartilage tissue engineering. Biomaterials 2016; 120:11-21. [PMID: 28024231 DOI: 10.1016/j.biomaterials.2016.12.015] [Citation(s) in RCA: 126] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 11/29/2016] [Accepted: 12/19/2016] [Indexed: 12/22/2022]
Abstract
Hydrogels prepared from poly(ethylene glycol) (PEG) are widely applied in tissue engineering, especially those derived from a combination of functional multi-arm star PEG and linear crosslinker, with an expectation to form a structurally ideal network. However, the poor mechanical strength still renders their further applications. Here we examined the relationship between the dynamics of the pre-gel solution and the mechanical property of the resultant hydrogel in a system consisting of 4-arm star PEG functionalized with vinyl sulfone and short dithiol crosslinker. A method to prepare mechanically strong hydrogel for cartilage tissue engineering is proposed. It is found that when gelation takes place at the overlap concentration, at which a slow relaxation mode just appears in dynamic light scattering (DLS), the resultant hydrogel has a local maximum compressive strength ∼20 MPa, while still keeps ultralow mass concentration and Young's modulus. Chondrocyte-laden hydrogel constructed under this condition was transplanted into the subcutaneous pocket and an osteochondral defect model in SCID mice. The in vivo results show that chondrocytes can proliferate and maintain their phenotypes in the hydrogel, with the production of abundant extracellular matrix (ECM) components, formation of typical chondrocyte lacunae structure and increase in Young's modulus over 12 weeks, as indicated by histological, immunohistochemistry, gene expression analyses and mechanical test. Moreover, newly formed hyaline cartilage was observed to be integrated with the host articular cartilage tissue in the defects injected with chondrocytes/hydrogel constructs. The results suggest that this hydrogel is a promising candidate scaffold for cartilage tissue engineering.
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Guo RH, Hua CC, Lin PC, Wang TY, Chen SA. Mesoscale aggregation properties of C60 in toluene and chlorobenzene. SOFT MATTER 2016; 12:6300-6311. [PMID: 27376417 DOI: 10.1039/c6sm00602g] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The mesoscale aggregation properties of C60 in two distinct aromatic solvents (toluene and chlorobenzene) and a practical range of concentrations (c = 1-2 and c = 1-5 mg mL(-1), respectively) were systematically explored by static/dynamic light scattering (SLS/DLS), small angle X-ray scattering (SAXS), depolarized dynamic light scattering (DDLS), and cryogenic transmission electron microscopy (cryo-TEM) analyses. The central observations were as follows: (1) aggregate species of sizes in the range of several hundred nanometers have been independently revealed by SLS, DLS, and DDLS analyses for both solvent systems. (2) DDLS and cryo-TEM measurements further revealed that while C60 clusters are notably anisotropic (rod-like) in chlorobenzene, they are basically isotropic (spherical) in toluene. (3) Detailed analyses of combined SLS and SAXS profiles suggested that varied, yet self-similar, solvent-induced aggregate units were responsible for the distinct (mesoscale) aggregation features noted above. (4) From a dynamic perspective, specially commissioned DLS measurements ubiquitously displayed two relaxation modes (fast and slow mode), with the second (slow) mode being q (wave vector) independent. While the fast mode in both solvent systems was basically diffusive by nature and leads to geometrical features in good agreement with the above static analyses, the slow mode was analyzed and tentatively suggested to reflect the effect of mutual confinement. (5) Micron-scale aggregate morphology of drop-cast thin films displays similar contrasting features for the two solvent media used. Overall, this study suggests that solvent-induced, nanoscale, aggregate units may be a promising factor to control a hierarchy of microscopic aggregation properties of C60 solutions and thin films.
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Affiliation(s)
- Rong-Hao Guo
- Department of Chemical Engineering, National Chung Cheng University, Chiayi 621, Taiwan.
| | - Chi-Chung Hua
- Department of Chemical Engineering, National Chung Cheng University, Chiayi 621, Taiwan.
| | - Po-Chang Lin
- National Synchrotron Radiation Research Center, Hsinchu 300, Taiwan
| | - Ting-Yu Wang
- Instrumentation Center, National Taiwan University, Taipei 106, Taiwan
| | - Show-An Chen
- Department of Chemical Engineering, National Tsing Hua University, Hsinchu 300, Taiwan
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9
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Wang J, Wu C. Reexamination of the Origin of Slow Relaxation in Semidilute Polymer Solutions—Reptation Related or Not? Macromolecules 2016. [DOI: 10.1021/acs.macromol.6b00298] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jianqi Wang
- Department of Chemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China
- Heifei National Laboratory for Physical Sciences at Microscale, Department of Chemical Physics, University of Science and Technology of China, Anhui, China
| | - Chi Wu
- Department of Chemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China
- Heifei National Laboratory for Physical Sciences at Microscale, Department of Chemical Physics, University of Science and Technology of China, Anhui, China
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10
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Raghavan V, Gupta M, Xiao Z, Gi Chae H, Liu T, Kumar S. Investigation of polyacrylonitrile solution inhomogeneity by dynamic light scattering. POLYM ENG SCI 2015. [DOI: 10.1002/pen.24084] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Vijay Raghavan
- School of Materials Science and Engineering, Georgia Institute of Technology; Atlanta Georgia 30332
| | - Murari Gupta
- Department of Industrial and Manufacturing Engineering; High-Performance Materials Institute, Florida State University; Tallahassee Florida 32310
| | - Zhiwei Xiao
- Department of Industrial and Manufacturing Engineering; High-Performance Materials Institute, Florida State University; Tallahassee Florida 32310
| | - Han Gi Chae
- School of Materials Science and Engineering, Georgia Institute of Technology; Atlanta Georgia 30332
| | - Tao Liu
- Department of Industrial and Manufacturing Engineering; High-Performance Materials Institute, Florida State University; Tallahassee Florida 32310
| | - Satish Kumar
- School of Materials Science and Engineering, Georgia Institute of Technology; Atlanta Georgia 30332
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11
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Affiliation(s)
- Jianqi Wang
- Department of Chemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong
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12
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Guo RH, Hsu CH, Hua CC, Chen SA. Colloidal aggregate and gel incubated by amorphous conjugated polymer in hybrid-solvent medium. J Phys Chem B 2015; 119:3320-31. [PMID: 25607342 DOI: 10.1021/acs.jpcb.5b00575] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A practical valuable amorphous conjugated polymer, poly(2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene (MEH-PPV), has been revealed to foster an abundance of micrometer-sized colloidal aggregates at relatively low concentration (below 1 wt %) in a hybrid-solvent medium that contains a nonsolvent, and the solution turned into gel by colloidal bridging after one-day aging at 30 °C. In contrast with typical polymer gels fostered by (anisotropic) chain cross-linking or planar packing on selective interacting sites, the MEH-PPV gel has been revealed (via dynamic light scattering, small-angle light scattering, time-sweep dynamic modulus and optical microscope) to first develop featureless aggregate clusters in solution and, as the solvent quality worsens with reduced system temperature, bridge themselves to form gel through a one-dimensional (1-D) to three-dimensional (3-D) kinetic pathway. Combined dynamic/static light scattering analyses, along with supporting scanning electron microscope image and molecular dynamics simulation, indicated a concomitant structural reorganization within the colloidal aggregates, where spontaneous chain packing was perceived to form local fiber-like materials that are elastic by nature (i.e., a q-independent decay rate). The near coincidence of the above-mentioned microscopic and macroscopic phase alterations led us to contend that similar fibrous materials have served as the exterior bridging agent to fabricate colloidal strands upon gelation. The present findings clarify previously enigmatic, much speculative, gelation phenomena of MEH-PPV, and shed light on the prospect of capitalizing on specific polymer-solvent interactions to incubate desirable colloidal aggregates and gels in room-temperature processing of practical valuable conjugated polymers.
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Affiliation(s)
- Rong H Guo
- Department of Chemical Engineering, National Chung Cheng University , Chiayi 621, Taiwan, Republic of China
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13
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Babaye Khorasani F, Poling-Skutvik R, Krishnamoorti R, Conrad JC. Mobility of Nanoparticles in Semidilute Polyelectrolyte Solutions. Macromolecules 2014. [DOI: 10.1021/ma501248u] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Firoozeh Babaye Khorasani
- Department of Chemical and
Biomolecular Engineering, University of Houston, Houston, Texas 77204-4004, United States
| | - Ryan Poling-Skutvik
- Department of Chemical and
Biomolecular Engineering, University of Houston, Houston, Texas 77204-4004, United States
| | - Ramanan Krishnamoorti
- Department of Chemical and
Biomolecular Engineering, University of Houston, Houston, Texas 77204-4004, United States
| | - Jacinta C. Conrad
- Department of Chemical and
Biomolecular Engineering, University of Houston, Houston, Texas 77204-4004, United States
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14
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Vyshivannaya OV, Laptinskaya TV. Dynamic light scattering in sols of a poly(N-vinylcaprolactam) and polyacrylamide mixture. POLYMER SCIENCE SERIES A 2012. [DOI: 10.1134/s0965545x12050136] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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15
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Tang Y, Duan J, Wu J. A laser light scattering study of complex formation between soybean peroxidase and poly(N-isopropylacrylamide-co-sodium styrene sulfonate). Colloids Surf A Physicochem Eng Asp 2012. [DOI: 10.1016/j.colsurfa.2011.12.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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16
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Lebedev VT, Mel’nikov AB, Török G, Vinogradova LV. Self-organization of sulfopolystyrene ionomers in solutions: Dependence on the polarity of the solution and the content of ionogenic groups in chains. POLYMER SCIENCE SERIES A 2011. [DOI: 10.1134/s0965545x11080049] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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18
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Schramm S, Blochowicz T, Gouirand E, Wipf R, Stühn B, Chushkin Y. Concentration fluctuations in a binary glass former investigated by x-ray photon correlation spectroscopy. J Chem Phys 2010; 132:224505. [DOI: 10.1063/1.3431537] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
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19
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Zettl U, Hoffmann ST, Koberling F, Krausch G, Enderlein J, Harnau L, Ballauff M. Self-Diffusion and Cooperative Diffusion in Semidilute Polymer Solutions As Measured by Fluorescence Correlation Spectroscopy. Macromolecules 2009. [DOI: 10.1021/ma901404g] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ute Zettl
- Physikalische Chemie I, University of Bayreuth, D-95440 Bayreuth, Germany
| | | | | | | | - Jörg Enderlein
- Institute of Physics, Georg August University, D-37077 Göttingen, Germany
| | - Ludger Harnau
- Max-Planck-Institut für Metallforschung, Heisenbergstrasse 3, D-70569 Stuttgart, Germany
- Institut für Theoretische und Angewandte Physik, Universität Stuttgart, Pfaffenwaldring 57, D-70569 Stuttgart, Germany
| | - Matthias Ballauff
- Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin, 14109 Berlin, Germany
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Zhou K, Li J, Lu Y, Zhang G, Xie Z, Wu C. Re-examination of Dynamics of Polyeletrolytes in Salt-Free Dilute Solutions by Designing and Using a Novel Neutral−Charged−Neutral Reversible Polymer. Macromolecules 2009. [DOI: 10.1021/ma900541x] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Kejin Zhou
- Shanghai-Hong Kong Joint Laboratory in Chemical Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Lu, Shanghai 200032, China
| | - Junfang Li
- The Hefei National Laboratory for Physical Sciences at Microscale, Department of Chemical Physics, University of Science and Technology of China, Hefei, China
| | - Yijie Lu
- The Hefei National Laboratory for Physical Sciences at Microscale, Department of Chemical Physics, University of Science and Technology of China, Hefei, China
| | - Guangzhao Zhang
- The Hefei National Laboratory for Physical Sciences at Microscale, Department of Chemical Physics, University of Science and Technology of China, Hefei, China
| | - Zuowei Xie
- Shanghai-Hong Kong Joint Laboratory in Chemical Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Lu, Shanghai 200032, China
- Department of Chemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China
| | - Chi Wu
- The Hefei National Laboratory for Physical Sciences at Microscale, Department of Chemical Physics, University of Science and Technology of China, Hefei, China
- Department of Chemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China
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22
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23
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Ge H, Jin F, Li J, Wu C. How Much Force Is Needed To Stretch a Coiled Chain in Solution? Macromolecules 2009. [DOI: 10.1021/ma9005523] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Hui Ge
- Department of Chemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong
| | - Fan Jin
- Department of Chemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong
| | - Junfang Li
- The Hefei National Laboratory of Physical Science at Microscale, Department of Chemical Physics, The University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Chi Wu
- Department of Chemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong
- The Hefei National Laboratory of Physical Science at Microscale, Department of Chemical Physics, The University of Science and Technology of China, Hefei, Anhui 230026, China
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24
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Grabowski CA, Mukhopadhyay A. Diffusion of Polystyrene Chains and Fluorescent Dye Molecules in Semidilute and Concentrated Polymer Solutions. Macromolecules 2008. [DOI: 10.1021/ma801035n] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | - Ashis Mukhopadhyay
- Department of Physics & Astronomy, Wayne State University, Detroit, Michigan 48201
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Gianneli M, Roskamp RF, Jonas U, Loppinet B, Fytas G, Knoll W. Dynamics of swollen gel layers anchored to solid surfaces. SOFT MATTER 2008; 4:1443-1447. [PMID: 32907110 DOI: 10.1039/b801468j] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We employ a dynamic micro light scattering technique to probe the thermal concentration fluctuations in surface-attached poly-N-isopropylacrylamide (PNIPAAm) gel layers swollen in ethanol as a good solvent. At the equilibrium swelling state, the relaxation function exhibits two decays in the time range between microseconds and seconds and the characteristic rates display a pure diffusive behavior. The fast cooperative diffusion increases with crosslinking density as a result of the decrease in the dynamic network mesh size. This increase is significantly stronger than the concentration dependence of the cooperative diffusion in uncrosslinked linear PNIPPAm solutions. Uniaxial swelling due to the surface attachment and structural inhomogeneities intrinsic to photo-crosslinked gels alter the dynamics of the surface anchored networks compared to the solutions. In contrast to the frozen inhomogeneities in conventional gels, the slow diffusion in the present anchored layers was found to be ergodic. It might relate to structural inhomogeneities but its nature is not clarified yet.
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Affiliation(s)
- Maria Gianneli
- Max Planck Institute for Polymer Research, P. O. Box 3148, Mainz, 55128, Germany and FO.R.T.H/IESL, P. O. Box 1527, 71110 Heraklion, Greece and Department of Materials Science & Technology, University of Crete, Greece
| | - Robert F Roskamp
- Max Planck Institute for Polymer Research, P. O. Box 3148, Mainz, 55128, Germany
| | - Ulrich Jonas
- Max Planck Institute for Polymer Research, P. O. Box 3148, Mainz, 55128, Germany and FO.R.T.H/IESL, P. O. Box 1527, 71110 Heraklion, Greece
| | | | - George Fytas
- Max Planck Institute for Polymer Research, P. O. Box 3148, Mainz, 55128, Germany and FO.R.T.H/IESL, P. O. Box 1527, 71110 Heraklion, Greece and Department of Materials Science & Technology, University of Crete, Greece
| | - Wolfgang Knoll
- Max Planck Institute for Polymer Research, P. O. Box 3148, Mainz, 55128, Germany
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