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Shen Z, Carrillo JMY, Sumpter BG, Wang Y. Mesoscopic two-point collective dynamics of glass-forming liquids. J Chem Phys 2023; 159:114501. [PMID: 37712790 DOI: 10.1063/5.0161866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 08/24/2023] [Indexed: 09/16/2023] Open
Abstract
The collective density-density and hydrostatic pressure-pressure correlations of glass-forming liquids are spatiotemporally mapped out using molecular dynamics simulations. It is shown that the sharp rise of structural relaxation time below the Arrhenius temperature coincides with the emergence of slow, nonhydrodynamic collective dynamics on mesoscopic scales. The observed long-range, nonhydrodynamic mode is independent of wave numbers and closely coupled to the local structural dynamics. Below the Arrhenius temperature, it dominates the slow collective dynamics on length scales immediately beyond the first structural peak in contrast to the well-known behavior at high temperatures. These results highlight a key connection between the qualitative change in mesoscopic two-point collective dynamics and the dynamic crossover phenomenon.
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Affiliation(s)
- Zhiqiang Shen
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Jan-Michael Y Carrillo
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Bobby G Sumpter
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Yangyang Wang
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
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2
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Abstract
We apply a scaling theory of semidilute polymer solutions to quantify solution properties of polysaccharides such as galactomannan, chitosan, sodium carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, xanthan, apple pectin, cellulose tris(phenyl carbamate), hydroxyethyl cellulose, hydroxypropyl cellulose, sodium hyaluronate, sodium alginate, and sodium κ-carrageenan. In particular, we obtain the molar mass of the chain segment inside a correlation blob M g = B̂ 3/(3ν-1) c 1/(1-3ν) as a function of concentration c, interaction parameter B̂, and exponent ν. Parameter B̂ assumes values B̂ g, B̂ th and M 0/N A 1/3 l for exponents v = 0.588, 0.5 and 1, respectively, where M 0 is the molar mass of a repeat unit, l is the projection length of a repeat unit, and N A is the Avogadro number. In the different solution regimes, the values of the B̂-parameters are extracted from the plateaus of the normalized specific viscosity ηsp (c)/M w c 1/(3ν-1), where M w is the weight-average molecular weight of the polymer chain. The values of the B̂-parameters are used in calculations of the excluded volume v, Kuhn length b, and crossover concentrations c*, c th, and c** into a semidilute polymer solution, a solution of overlapping thermal blobs and a concentrated polymer solution, respectively. This information is summarized as a diagram of states of different polysaccharide solution regimes by implementing a v/bl 2 and c/c** representation. The scaling approach is extended to the entangled solution regime, allowing us to obtain the chain packing number, P̃ e. This completes the set of parameters {B̂ g, B̂ th, P̃ e} which uniquely describes the static and dynamic properties of a polysaccharide solution.
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Affiliation(s)
- Andrey V. Dobrynin
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599-3290, United States
| | - Michael Jacobs
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599-3290, United States
| | - Ryan Sayko
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599-3290, United States
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4
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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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5
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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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6
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Handle PH, Rovigatti L, Sciortino F. q-Independent Slow Dynamics in Atomic and Molecular Systems. PHYSICAL REVIEW LETTERS 2019; 122:175501. [PMID: 31107067 DOI: 10.1103/physrevlett.122.175501] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Indexed: 06/09/2023]
Abstract
Investigating million-atom systems for very long simulation times, we demonstrate that the collective density-density correlation time (τ_{α}) in simulated supercooled water and silica becomes wave-vector independent (q^{0}) when the probing wavelength is several times larger than the interparticle distance. The q independence of the collective density-density correlation functions, a feature clearly observed in light-scattering studies of some soft-matter systems, is thus a genuine feature of many (but not all) slow-dynamics systems, either atomic, molecular, or colloidal. Indeed, we show that when the dynamics of the density fluctuations includes particle-type diffusion, as in the case of the Lennard-Jones binary-mixture model, the q^{0} regime does not set in and the relaxation time continues to scale as τ_{α}∼q^{-2} even at small q.
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Affiliation(s)
- Philip H Handle
- Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 5, I-00185 Roma, Italy
| | - Lorenzo Rovigatti
- Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 5, I-00185 Roma, Italy
- CNR-ISC, UoS Sapienza, Piazzale Aldo Moro 5, I-00185 Roma, Italy
| | - Francesco Sciortino
- Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 5, I-00185 Roma, Italy
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7
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Zhu H, Cui Y, Wang J, Qiu H. Formation of disk-like micelles of triblock copolymers in frustrating solvents. RSC Adv 2019; 9:9443-9448. [PMID: 35520696 PMCID: PMC9062166 DOI: 10.1039/c9ra01145e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Accepted: 03/18/2019] [Indexed: 12/28/2022] Open
Abstract
Coil–coil block copolymers rarely self-assemble into flat low-curvature micelles due to the lack of proper interchain association. Here, we report a facile route to prepare disk-like micelles through the self-assembly of amphiphilic polystyrene-b-polybutadiene-b-poly(2-vinylpyridine) triblock copolymers in a mixture of acetone and cyclohexane, which shows distinct selectivity towards the PS, PB and P2VP blocks. Subtle solvation/aggregation of these blocks in this frustrating solvent system provides access to low-curvature micellar structures, and thus favors the formation of uniform disk-like micelles. Further variation of the volume ratio of the mixed solvents also leads to the emergence of other interesting morphologies, including disk arrays, disk clusters and perforated disk-like micelles. This work provides a complementary insight into the solution self-assembly of block copolymers in a view of selective solvents and demonstrates a distinctive pathway to unconventional micellar nanostructures through the use of complex solvent systems. Self-assembly of amphiphilic triblock copolymers in a frustrating solvent system leads to the formation of various low-curvature micellar structures.![]()
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Affiliation(s)
- Hongyan Zhu
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences Shanghai 201800 China .,University of Chinese Academy of Sciences Beijing 100049 China
| | - Yan Cui
- School of Chemistry and Chemical Engineering, State Key Lab of Metal Matrix Composites, Shanghai Jiao Tong University Shanghai 200240 China
| | - Jie Wang
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences Shanghai 201800 China .,Shanghai Advanced Research Institute, Zhangjiang Lab, Chinese Academy of Sciences Shanghai 201204 China
| | - Huibin Qiu
- School of Chemistry and Chemical Engineering, State Key Lab of Metal Matrix Composites, Shanghai Jiao Tong University Shanghai 200240 China
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8
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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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9
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Martinetti L, Carey-De La Torre O, Schweizer KS, Ewoldt RH. Inferring the Nonlinear Mechanisms of a Reversible Network. Macromolecules 2018. [DOI: 10.1021/acs.macromol.8b01295] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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10
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Rovigatti L, Nava G, Bellini T, Sciortino F. Self-Dynamics and Collective Swap-Driven Dynamics in a Particle Model for Vitrimers. Macromolecules 2018. [DOI: 10.1021/acs.macromol.7b02186] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Lorenzo Rovigatti
- CNR-ISC,
Uos Sapienza, Piazzale A. Moro 2, 00185 Roma, Italy
- Department
of Physics, Sapienza, Universitá di Roma, Piazzale Aldo
Moro 2, I-00185, Roma, Italy
| | - Giovanni Nava
- Department
of Medical Biotechnology and Translational Medicine, Universita degli Studi di Milano, via Fratelli Cervi 93, I-20090 Segrate, MI, Italy
| | - Tommaso Bellini
- Department
of Medical Biotechnology and Translational Medicine, Universita degli Studi di Milano, via Fratelli Cervi 93, I-20090 Segrate, MI, Italy
| | - Francesco Sciortino
- Department
of Physics, Sapienza, Universitá di Roma, Piazzale Aldo
Moro 2, I-00185, Roma, Italy
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11
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Study of autocorrelation function of polymer and polymer–nanocomposite solutions using dynamic light scattering method. JOURNAL OF POLYMER RESEARCH 2017. [DOI: 10.1007/s10965-017-1368-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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12
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Nava G, Rossi M, Biffi S, Sciortino F, Bellini T. Fluctuating Elasticity Mode in Transient Molecular Networks. PHYSICAL REVIEW LETTERS 2017; 119:078002. [PMID: 28949673 DOI: 10.1103/physrevlett.119.078002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Indexed: 06/07/2023]
Abstract
Transient molecular networks, a class of adaptive soft materials with remarkable application potential, display complex, and intriguing dynamic behavior. By performing dynamic light scattering on a wide angular range, we study the relaxation dynamics of a reversible network formed by DNA tetravalent nanoparticles, finding a slow relaxation mode that is wave vector independent at large q and crosses over to a standard q^{-2} viscoelastic relaxation at low q. Exploiting the controlled properties of our DNA network, we attribute this mode to fluctuations in local elasticity induced by connectivity rearrangement. We propose a simple beads and springs model that captures the basic features of this q^{0} behavior.
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Affiliation(s)
- Giovanni Nava
- Department of Medical Biotechnology and Translational Medicine, Università degli Studi di Milano, via Fratelli Cervi 93, I-20090 Segrate, Milano, Italy
| | - Marina Rossi
- Department of Medical Biotechnology and Translational Medicine, Università degli Studi di Milano, via Fratelli Cervi 93, I-20090 Segrate, Milano, Italy
| | - Silvia Biffi
- Department of Medical Biotechnology and Translational Medicine, Università degli Studi di Milano, via Fratelli Cervi 93, I-20090 Segrate, Milano, Italy
| | - Francesco Sciortino
- Department of Physics and CNR-ISC, Sapienza Università di Roma, Piazzale Aldo Moro 2, I-00185 Roma, Italy
| | - Tommaso Bellini
- Department of Medical Biotechnology and Translational Medicine, Università degli Studi di Milano, via Fratelli Cervi 93, I-20090 Segrate, Milano, Italy
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13
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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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14
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Kishore S, Chen Y, Ravindra P, Bhatia SR. The effect of particle-scale dynamics on the macroscopic properties of disk-shaped colloid–polymer systems. Colloids Surf A Physicochem Eng Asp 2015. [DOI: 10.1016/j.colsurfa.2015.06.056] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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15
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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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16
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A dynamic light scattering study of hydrogels with the addition of surfactant: a discussion of mesh size and correlation length. Polym J 2014. [DOI: 10.1038/pj.2014.114] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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17
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Wang W, Arne Sande S. Monitoring of macromolecular dynamics during a chemical cross-linking process of hydroxyethylcellulose derivatives by dynamic light scattering. Eur Polym J 2014. [DOI: 10.1016/j.eurpolymj.2014.06.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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18
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Arenas-Gómez B, Vinceković M, Garza C, Castillo R. Worm-like micelles in water solutions of 1, 4 poly (1, 3-butadiene)-polyethylene oxide diblock copolymer. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2014; 37:10. [PMID: 24965154 DOI: 10.1140/epje/i2014-14051-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Accepted: 05/28/2014] [Indexed: 06/03/2023]
Abstract
The main purpose of this study is to determine for the first time the structure of the self-assembled aggregates in the system made of 1,4 poly(1,3-butadiene)-polyethylene oxide diblock copolymer (IUPAC name: poly(but-2-ene-1,4-diyl)-block-polyoxyethylene) and water, and the rheological behavior of the solution. The degree of polymerization of the polybutadiene and polyethylene oxide blocks is 37 and 45, respectively. The diblock copolymer concentration was limited to be ≤2.5 wt% to avoid phase separation. Small X-ray scattering revealed that the diblock copolymer self-assembles in worm-like micelles with a diameter of ∼ 12 nm. This system does not closely follow the rheological behavior of worm-like micelle solutions made of typical surfactants. The system steadily shear thins reaching very low viscosity values at large shear rates, however there are not shear-thickening peaks. In thixotropic loops, the micellar solution does not present hysteresis. The viscoelastic spectra do not follow the Maxwell model at low and intermediate frequencies. This uncommon behavior for a worm-like micellar system is explained by the slow dynamics of the self-assembly. The extremely high hydrophobicity of the polybutadiene block does not allow any micellar rearrangement.
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Affiliation(s)
- Brisa Arenas-Gómez
- Instituto de Física, Universidad Nacional Autónoma de México, P. O. Box 20-264, 01000, México, D. F., México
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19
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Ruggeri F, Zhang F, Lind T, Bruce ED, Lau BLT, Cárdenas M. Non-specific interactions between soluble and induce irreversible changes in the properties of bilayers. SOFT MATTER 2013; 9:4219-4226. [PMID: 25419552 DOI: 10.1039/c3sm27769k] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Soluble in the extracellular matrix experience a crowded environment. However, most of the biophysical studies performed to date have focused on concentrations within the dilute regime (well below the mM range). Here, we systematically studied the interaction of model cell membrane systems (giant unilamellar vesicles and supported bilayers) with soluble globular , bovine serum albumin, and lysozyme at physiologically relevant concentrations. To mimic the extracellular environment more closely, we also used fetal bovine serum as a good representative of a biomimetic mixture. We found that regardless of the used (and thus of their biological function), the interactions between a model cell membrane and these are determined by their physico-chemical characteristics, mainly their dipolar character (or charged patches). In this paper we discuss the specificity and reversibility of these interactions and their potential implications on the living cells. In particular, we report initial evidence for an additional role of in cell membranes: that of reducing the effects of non-specific of soluble on the cell membrane.
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Affiliation(s)
- Francesca Ruggeri
- Institute of Chemistry and Nano-Science Center, University of Copenhagen, Universitetparken 5, DK 2100, Copenhagen, Denmark.
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20
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Shin H, Pascal TA, Goddard WA, Kim H. Scaled Effective Solvent Method for Predicting the Equilibrium Ensemble of Structures with Analysis of Thermodynamic Properties of Amorphous Polyethylene Glycol–Water Mixtures. J Phys Chem B 2013; 117:916-27. [DOI: 10.1021/jp310422q] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
| | - Tod A. Pascal
- Materials and Process Simulation
Center, California Institute of Technology, Pasadena, California 91125, United States
| | - William A. Goddard
- Materials and Process Simulation
Center, California Institute of Technology, Pasadena, California 91125, United States
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21
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de Molina PM, Herfurth C, Laschewsky A, Gradzielski M. Structure and dynamics of networks in mixtures of hydrophobically modified telechelic multiarm polymers and oil in water microemulsions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:15994-16006. [PMID: 23075139 DOI: 10.1021/la303673a] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The structural and dynamical properties of oil-in-water (O/W) microemulsions (MEs) modified with telechelic polymers of different functionality (e.g., number of hydrophobically modified arms, f) were studied by means of dynamic light scattering (DLS), small-angle neutron scattering (SANS), and high frequency rheology measurements as a function of the polymer architecture and the amount of added polymer. For this purpose, we employed tailor-made hydrophobically end-capped poly(N,N-dimethylacrylamide) star polymers of a variable number of endcaps, f, of different alkyl chain lengths, synthesized by the reversible addition-fragmentation chain transfer method. The addition of the different end-capped polymers to an uncharged ME of O/W droplets leads to a large enhancement of the viscosity of the systems. SANS experiments show that the O/W ME droplets are not changed upon the addition of the polymer, and its presence only changes the interdroplet interactions. The viscosity increases largely upon addition of a polymer, and this enhancement depends pronouncedly on the alkyl length of the hydrophobic sticker as it controls the residence time in a ME droplet. Similarly, the high frequency modulus G(0) depends on the amount of added polymer but not on the sticker length. G(0) was found to be directly proportional to f - 1. The onset of network formation is shifted to a lower number of stickers per ME droplet with increasing f, and the network formation becomes more effective. Thus, the dynamics of network formation are controlled by the polymer architecture. The effect on the dynamics seen by DLS is even more pronounced. Upon increasing the polymer concentration, slower relaxation modes appear that become especially pronounced with increasing number of arms. The relaxation dynamics are correlated to the rheological relaxation, and both are controlled by the polymer architecture.
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Affiliation(s)
- Paula Malo de Molina
- Stranski-Laboratorium für Physikalische und Theoretische Chemie, Institut für Chemie, Technische Universität Berlin, Berlin, Germany.
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22
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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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23
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Parashchuk OD, Laptinskaya TV, Paraschuk DY. Macromolecular dynamics of conjugated polymer in donor–acceptor blends with charge transfer complex. Phys Chem Chem Phys 2011; 13:3775-81. [DOI: 10.1039/c0cp01710h] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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24
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25
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Aschi A, Trabelsi S, Gharbi A. Study of solution properties of poly(deamino-tyr-tyr carbonate hexyl ester) by light scattering and viscometry in dilute and semidilute regime. POLYM ENG SCI 2010. [DOI: 10.1002/pen.21676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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26
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Yin H, Lin Y, Huang J. Microstructures and rheological dynamics of viscoelastic solutions in a catanionic surfactant system. J Colloid Interface Sci 2009; 338:177-83. [DOI: 10.1016/j.jcis.2009.05.076] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2009] [Revised: 05/28/2009] [Accepted: 05/30/2009] [Indexed: 11/25/2022]
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27
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Ganguly R, Choudhury N, Aswal VK, Hassan PA. Pluronic L64 Micelles near Cloud Point: Investigating the Role of Micellar Growth and Interaction in Critical Concentration Fluctuation and Percolation. J Phys Chem B 2008; 113:668-75. [DOI: 10.1021/jp808304w] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- R. Ganguly
- Chemistry Division, Theoretical Chemistry Section, and Solid State Physics Division, Bhabha Atomic Research Center, Mumbai 400 085, India
| | - N. Choudhury
- Chemistry Division, Theoretical Chemistry Section, and Solid State Physics Division, Bhabha Atomic Research Center, Mumbai 400 085, India
| | - V. K. Aswal
- Chemistry Division, Theoretical Chemistry Section, and Solid State Physics Division, Bhabha Atomic Research Center, Mumbai 400 085, India
| | - P. A. Hassan
- Chemistry Division, Theoretical Chemistry Section, and Solid State Physics Division, Bhabha Atomic Research Center, Mumbai 400 085, India
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28
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Aggregation behavior of new cyclic saturated copolymers synthesized via ring-opening metathesis polymerization. POLYMER 2008. [DOI: 10.1016/j.polymer.2008.08.047] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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29
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Denkova AG, Mendes E, Coppens MO. Effects of Salts and Ethanol on the Population and Morphology of Triblock Copolymer Micelles in Solution. J Phys Chem B 2008; 112:793-801. [DOI: 10.1021/jp075114c] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- A. G. Denkova
- DelftChemTech, Delft University of Technology, Julianalaan 136, 2628 BL Delft, The Netherlands, and Isermann Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180
| | - E. Mendes
- DelftChemTech, Delft University of Technology, Julianalaan 136, 2628 BL Delft, The Netherlands, and Isermann Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180
| | - M.-O. Coppens
- DelftChemTech, Delft University of Technology, Julianalaan 136, 2628 BL Delft, The Netherlands, and Isermann Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180
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Buhler E, Candau SJ, Kolomiets E, Lehn JM. Dynamical properties of semidilute solutions of hydrogen-bonded supramolecular polymers. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2007; 76:061804. [PMID: 18233862 DOI: 10.1103/physreve.76.061804] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2007] [Indexed: 05/25/2023]
Abstract
The dynamical properties of semidilute solutions of supramolecular polymers formed from molecular recognition directed association between monomers bearing complementary hydrogen bonding groups were investigated by rheological and dynamic light scattering experiments. The steady-state flow curves showed a shear banding type instability, namely the occurrence of a stress plateau sigma(p) above a critical shear rate .gamma(c) . The values of sigma(p)and .gamma(c) were found to be of the same order of magnitude as those of the elastic plateau modulus and the inverse stress relaxation time, respectively. The above features are in agreement with the theoretical predictions based on the reptation model. Dynamic light scattering experiments showed the presence in the autocorrelation function of the concentration fluctuations of a slow viscoelastic relaxation process that is likely to be of Rouse type.
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Affiliation(s)
- Eric Buhler
- Matière et Systèmes Complexes, UMR CNRS 7057, Université Paris 7-Denis Diderot, Bâtiment Condorcet, CC 7056, Paris cedex 13, France
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31
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Ganguly R, Aswal VK, Hassan PA. Room temperature sphere-to-rod growth and gelation of PEO–PPO–PEO triblock copolymers in aqueous salt solutions. J Colloid Interface Sci 2007; 315:693-700. [PMID: 17707391 DOI: 10.1016/j.jcis.2007.07.026] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2007] [Revised: 06/29/2007] [Accepted: 07/13/2007] [Indexed: 11/20/2022]
Abstract
The effects of NaCl and KF on the sphere-to-rod micellar growth behavior of triblock copolymers having two different compositions, (EO)20(PO)70(EO)20 (P123) and (EO)26(PO)40(EO)26 (P85), have been studied by dynamic light scattering (DLS), small angle neutron scattering (SANS) and dilute solution viscometry. NaCl can effectively tune the sphere-to-rod growth temperature of the micelles of both these copolymers and induce micellar growth down to the room temperature and below. The growth behavior is found to be dependent on the composition of the copolymer as P123 being more hydrophobic shows the room temperature growth in the presence of ethanol at significantly lesser NaCl concentration than the less hydrophobic copolymer P85. DLS studies depict for the first time the growth driven transition of the copolymer solutions from dilute to semi-dilute regime as a function of copolymer and salt concentrations. KF can also induce room temperature growth of the P123 micelles at lesser salt concentration than NaCl but it fails to induce any such growth of the P85 micelles. A pseudo-binary temperature-concentration phase diagram on 15% copolymer solutions shows the variation of the sphere-to-rod transition temperature and the cloud point of the copolymer solutions as a function of salt concentration.
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Affiliation(s)
- R Ganguly
- Chemistry Division, Bhabha Atomic Research Center, Mumbai 400 085, India.
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32
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Kostko AF, Anisimov MA, Sengers JV. Dynamics of critical fluctuations in polymer solutions. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2007; 76:021804. [PMID: 17930058 DOI: 10.1103/physreve.76.021804] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2007] [Indexed: 05/25/2023]
Abstract
Using dynamic light scattering we have investigated the time dependence of fluctuations near the critical point of phase separation in solutions of polystyrene in cyclohexane with polymer molecular weights ranging from 196,000 to 11.4 x 10(6) g mol(-1). At the lowest polymer molecular weight the dynamic correlation function follows a single-exponential decay with a decay rate that can be represented by the mode-coupling theory of critical dynamics but with a mesoscopic viscosity that characterizes the hydrodynamic environment of the polymers in the solution. At all higher polymer molecular weights two distinct dynamic modes are observed, a slow and a fast mode, that originate from a coupling of the critical concentration fluctuations with viscoelastic relaxation of the polymer chain in solutions. This coupling causes an additional slowing down of the fluctuations on top of the well-known critical slowing down expected in the absence of a coupling between the two modes. From an analysis of the time dependence of the experimental dynamic correlation functions in terms of a theory of coupling of dynamic modes we are able to determine the viscoelastic properties of the polymers in the solution. These viscoelastic properties diverge in the theta-point limit of infinite polymer molecular weight.
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Affiliation(s)
- A F Kostko
- Chemical and Life Sciences Engineering, School of Engineering, Virginia Commonwealth University, Richmond, Virginia 23284, USA
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33
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Štěpánek P, Tuzar Z, Kadlec P, Kříž J. A Dynamic Light Scattering Study of Fast Relaxations in Polymer Solutions. Macromolecules 2007. [DOI: 10.1021/ma0620518] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- P. Štěpánek
- Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Z. Tuzar
- Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - P. Kadlec
- Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - J. Kříž
- Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Prague, Czech Republic
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34
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Takenaka M, Nishitsuji S, Hasegawa H. Quantitative comparison between dynamic structure factors obtained experimentally and those calculated with Doi-Onuki theory. J Chem Phys 2007; 126:064903. [PMID: 17313240 DOI: 10.1063/1.2434956] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
This paper reports results of quantitative comparison between dynamic structure factors obtained experimentally and those calculated by using the Doi and Onuki (DO) theory for semidilute polymer solutions. The authors obtained the dynamic structure factors with dynamic light scattering (DLS) experiment while the dynamic structure factors were calculated by using DO theory with osmotic compressibility, viscoelastic relaxation function, and friction coefficient which are obtained independently of DLS experiment. Calculated dynamic structure factors agree with experimental ones well and can express the q-dependent fast modes and the q-insensitive slow mode which experimental ones show. The authors estimated the characteristic parameters, interdiffusion coefficient and cooperative diffusion coefficient, from experimental and calculated results by using the procedure proposed by Einaga and Fujita [Polymer 40, 565 (1999)]. The estimated parameters for the DLS experiment agree with those for the calculation. These agreements in dynamic structure factors and the parameters indicate that DO theory can describe well the relaxation processes of semidilute polymer solutions.
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Affiliation(s)
- Mikihito Takenaka
- Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
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35
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Svanberg C, Uematsu T, Berntsen P, Jacobsson P. New class of dynamics in concentrated polymer gels. J Chem Phys 2007; 126:051103. [PMID: 17302464 DOI: 10.1063/1.2432884] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We show that concentrated poly(methyl methacrylate) solution exhibits a new class of coupled dynamics, which can be regarded as an intermediate between the collective diffusion of solutions and the structural relaxations of glasses. This class of dynamics have a relaxation rate that is directly proportional to the wave vector. The transition from diffusive to coupled collective dynamics occurs at smaller length scales with increasing polymer concentration and decreasing temperature. The experimental observations can be understood by considering the contributions from physical cross-links interconnected by stiff polymer segments.
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Affiliation(s)
- C Svanberg
- Department of Applied Physics, Chalmers University of Technology, SE-412 96 Göteborg, Sweden.
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36
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Chen H, Ye X, Zhang G, Zhang Q. Dynamics of thermoresponsive PNIPAM-g-PEO copolymer chains in semi-dilute solution. POLYMER 2006. [DOI: 10.1016/j.polymer.2006.09.062] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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37
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38
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Oikawa H, Korenaga T, Nakanishi H. Dynamic light scattering study on sol-gel transition of poly(γ-benzyl L-glutamate)-toluene solutions. J MACROMOL SCI B 2006. [DOI: 10.1080/00222349708220416] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Hidetoshi Oikawa
- a Institute for Chemical Reaction Science Tohoku University , Katahira 2-1-1, Aoba-ku, Sendai, 980-77, Japan
| | - Tatsumi Korenaga
- a Institute for Chemical Reaction Science Tohoku University , Katahira 2-1-1, Aoba-ku, Sendai, 980-77, Japan
| | - Hachiro Nakanishi
- a Institute for Chemical Reaction Science Tohoku University , Katahira 2-1-1, Aoba-ku, Sendai, 980-77, Japan
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39
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Gupta A, Mohanty B, Bohidar HB. Flory temperature and upper critical solution temperature of gelatin solutions. Biomacromolecules 2006; 6:1623-7. [PMID: 15877386 DOI: 10.1021/bm0492430] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The Flory temperatures (theta) measured by turbidity experiments performed on gelatin solutions were found to be 12 +/- 0.3, 13 +/- 0.3, 14 +/- 0.3, 14.5 +/- 0.3, and 15 +/- 0.3 degrees C for salt concentrations 0.1, 0.075, 0.05, 0.025, and 0 M (NaCl), respectively. Estimated persistence length (l(p)) of this weakly charged polyelectrolyte could be deduced from the Benoit and Doty (J. Phys. Chem. 1953, 57, 958) relationship with the approximation that this biopolymer assumes a compact near-globular shape at Flory temperature, implying l(p) = 9(R(h))(2)/(5L(m)), where L(m) is the contour length and R(h) is the hydrodynamic radius. It was found that l(p) approximately 2.2 +/- 0.2 nm at room temperature (20 degrees C), invariant of salt concentration. The Flory expansion factor (alpha= R(h)(T)/R(h)(theta) = 1.5+/-0.2) was found to be almost constant. theta-Composition for this biopolymer was deduced from turbidimitric titration of aqueous gelatin solutions with the alcohols methanol, ethanol, 2-propanol, and tert-butyl alcohol. It appears that hydrophobic interactions play a crucial role in causing chain collapse at theta-temperature and composition.
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Affiliation(s)
- Amarnath Gupta
- School of Physical Sciences, Jawaharlal Nehru University, New Delhi-110067, India
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40
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Michailidou VN, Loppinet B, Vo DC, Prucker O, Rühe J, Fytas G. Dynamics of end-grafted polystyrene brushes in theta solvents. ACTA ACUST UNITED AC 2006. [DOI: 10.1002/polb.21016] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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41
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Luo S, Xu J, Zhang Y, Liu S, Wu C. Double Hydrophilic Block Copolymer Monolayer Protected Hybrid Gold Nanoparticles and Their Shell Cross-Linking. J Phys Chem B 2005; 109:22159-66. [PMID: 16853883 DOI: 10.1021/jp0549935] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This paper describes the syntheses of core/shell gold nanoparticles stabilized with a monolayer of double hydrophilic block copolymer and their stimuli responsiveness before and after shell cross-linking. The hybrid nanoparticles consist of gold core, cross-linkable poly(2-(dimethylamino)ethyl methacrylate) (PDMA) inner shell, and poly(ethylene oxide) (PEO) corona. First, diblock copolymer PEO-b-PDMA was prepared via the reversible addition-fragmentation chain transfer (RAFT) technique using a PEO-based macroRAFT agent. The dithioester end group of PEO-b-PDMA diblock copolymer was reduced to a thiol end group. The obtained PEO-b-PDMA-SH was then used to prepare diblock copolymer stabilized gold nanoparticles by the "grafting-to" approach. 1,2-Bis(2-iodoethoxy)ethane (BIEE) was utilized to selectively cross-link the PDMA residues in the inner shell. The stimuli responsiveness and colloidal stability of core/shell gold nanoparticles before and after shell cross-linking were characterized by laser light scattering (LLS), UV-vis transmittance, and transmission electron microscopy (TEM). At pH 9, the average hydrodynamic radius Rh of non-cross-linked hybrid gold nanoparticles starts to increase above 35 degrees C due to the lower critical solution temperature (LCST) phase behavior of the PDMA blocks in the inner shell. In contrast, Rh of the shell cross-linked gold nanoparticles were essentially independent of temperature. Core/shell gold nanoparticles before and after shell cross-linking exhibit reversible swelling on varying the solution pH. Compared to non-cross-linked core/shell gold nanoparticles, shell cross-linking of the hybrid gold nanoparticles leads to permanent core/shell nanostructures with much higher colloidal stability and physically isolates the gold core from the external environment.
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Affiliation(s)
- Shizhong Luo
- Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui, 230026, China
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42
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Wieczorek SA, Freyssingeas E, Hołyst R. Relaxation Processes in Semidilute Solutions of Polymers in Liquid Crystal Solvents. J Phys Chem B 2005; 109:16252-62. [PMID: 16853066 DOI: 10.1021/jp0510950] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We investigate the relaxation phenomena in a polymer (polystyrene)/liquid crystal (4-cyano-4'-n-octyl-biphenyl) system, in its homogeneous isotropic phase near the isotropic-isotropic, isotropic-nematic, and isotropic-smectic coexistence curve, using both polarized and depolarized photon correlation spectroscopy (PCS). We study this system for different polystyrene molecular weights (4750, 12 500, and 65 000 g/mol), different compositions (50, 40, 30, and 10% polystyrene (PS) by weight), and different temperatures close to phase boundaries. First of all, we determine the phase diagrams of this system for the different molecular weights. The shape of the phase diagrams strongly depends on the molecular weight. However, in all cases, at low temperatures, these systems separate into an almost pure liquid crystalline (LC) phase and polystyrene-rich phase. PCS measurements show that the relaxation processes in the homogeneous phase are not affected by the proximity of the nematic, or smectic, boundaries (even at a temperature of 0.1 degrees C above the phase separation in two phases). In polarized PCS experiments, we always see three relaxation processes well separated in time: one, very fast, with a relaxation time of the order of 10(-5) s; a second one with a relaxation time within the range 10(-2)-10(-3) s; and a last one, very slow, with a relaxation time of the order of 1 s. Both the fast and slow modes are independent of the wave vector magnitude, while the intermediate relaxation process is diffusive. In depolarized PCS experiments, the intermediate mode disappears and only the fast and slow relaxation processes remain, and they are independent of the magnitude of the wave vector. The diffusive mode is the classical diffusive mode, which is associated with the diffusion of polymer chains in all polymer solutions. The fast mode is due to the rotational diffusion of 4-cyano-4'-n-octyl-biphenyl (8CB) molecules close to polystyrene chains (transient network). Finally, we assign the slowest mode to reorientational processes of small aggregates of PS chains that are not dissolved in 8CB.
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Affiliation(s)
- Stefan A Wieczorek
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland.
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43
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Abstract
Microrheology of semidilute polymer solutions is investigated. In this paper we calculate a response function of a probe particle embedded in a semidilute polymer solution by analyzing the two-fluid model. We find that when the size of the probe particle is comparable to the viscoelastic length, the response from the longitudinal compression modes becomes more important than that of the transverse shear modes. As a result, depending on the circumstances, the obtained complex shear modulus cannot be well approximated by that measured in macroscopic rheology experiments. The present results are due to the dynamical asymmetry coupling and the existence of the cooperative dynamics, which are intrinsic to entangled polymer solutions.
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Affiliation(s)
- Akira Furukawa
- Department of Physics, Graduateschool of Science, Kyoto University, Kyoto 606-8502, Japan
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44
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Buhler E, Oelschlaeger C, Waton G, Candau SJ. Viscoelastic Properties of Hydrocarbon/Fluorocarbon Mixed Wormlike Micelles at High Ionic Strength. J Phys Chem B 2004. [DOI: 10.1021/jp049466k] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- E. Buhler
- Groupe de Dynamique des Phases Condensées, UMR No. 5581 CNRS, Université de Montpellier II, Case Courrier 26, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France, and Laboratoire de Dynamique des Fluides Complexes, UMR No. 7506 CNRS, Université Louis Pasteur, 4, rue Blaise Pascal, 67070 Strasbourg Cedex, France
| | - C. Oelschlaeger
- Groupe de Dynamique des Phases Condensées, UMR No. 5581 CNRS, Université de Montpellier II, Case Courrier 26, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France, and Laboratoire de Dynamique des Fluides Complexes, UMR No. 7506 CNRS, Université Louis Pasteur, 4, rue Blaise Pascal, 67070 Strasbourg Cedex, France
| | - G. Waton
- Groupe de Dynamique des Phases Condensées, UMR No. 5581 CNRS, Université de Montpellier II, Case Courrier 26, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France, and Laboratoire de Dynamique des Fluides Complexes, UMR No. 7506 CNRS, Université Louis Pasteur, 4, rue Blaise Pascal, 67070 Strasbourg Cedex, France
| | - S. J. Candau
- Groupe de Dynamique des Phases Condensées, UMR No. 5581 CNRS, Université de Montpellier II, Case Courrier 26, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France, and Laboratoire de Dynamique des Fluides Complexes, UMR No. 7506 CNRS, Université Louis Pasteur, 4, rue Blaise Pascal, 67070 Strasbourg Cedex, France
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45
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Freyssingeas E, Graca M, Wieczorek SA, Hołyst R. Relaxation processes in mixtures of liquid crystals and polymers near phase boundaries and during phase separation. J Chem Phys 2004; 120:8277-82. [PMID: 15267748 DOI: 10.1063/1.1691023] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We present experimental studies of the relaxation of concentration fluctuations in a semidilute solution of polystyrene (PS) (30% by weight) in 4-cyano-4'-n-octyl-biphenyl (8CB) (70% by weight) using the photon correlation spectroscopy (PCS). In the homogeneous phase there are two modes of relaxation. The slow one (typical time scale is taus = 0.001 s) is due to the diffusion of polymer chains (of molecular mass 65,000) in the LC matrix (of molecular mass 290), while the fast one has the time scale of the order of tauf approximately 0.00001 s. The amplitude of the fast mode is much weaker than the one for the slow mode. Moreover it does not depend on the scattering wave vector, q. The value of the diffusion coefficient, Dc = 1/(tausq2) for the slow mode decreases with temperature according to the Arhenius law until we reach the coexistence curve. Its value close to the coexistence is Dc = 4 x 10(5) nm2/s and the activation energy in the homogeneous mixture is Ec=127 kJ/mol. If we gradually undercool the mixture below the coexistence into the metastable two-phase region without inducing the phase separation we find unexpectedly that Dc does not change with temperature even 4 degrees below the coexistence curve. The characteristic time of the fast mode does not depend on the scattering wave vector indicating that it is related to the transient gel structure. We have shown that it is possible to measure the short time relaxation of concentration fluctuations during the phase separation in the mixture. At low temperature close to the isotropic-nematic phase transition we have observed that the relaxation is well separated in time from the typical time of the domain growth. This relaxation mode is characterized by the large diffusion coefficient D = 2 x 10(8) nm2/s. The mode probably comes from the coupling between the orientational dynamics of liquid crystals and the transient gel structure of polymers.
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Affiliation(s)
- E Freyssingeas
- Ecole Normale Superieure, Labo de Physique, 46 Allee d'Italie, Lyon, France
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46
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Yakubov GE, Loppinet B, Zhang H, Rühe J, Sigel R, Fytas G. Collective dynamics of an end-grafted polymer brush in solvents of varying quality. PHYSICAL REVIEW LETTERS 2004; 92:115501. [PMID: 15089145 DOI: 10.1103/physrevlett.92.115501] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2003] [Indexed: 05/24/2023]
Abstract
The dynamic structure of a chemically end-grafted polystyrene brush bathed in solvents of varying interactions was studied by evanescent wave dynamic light scattering. It reveals distinct behavior under good and poor solvent conditions. The cooperative diffusion is a generic feature of a good solvent environment, whereas a second slow relaxation mode appears in the theta solvent regime. Its characteristics resemble self-diffusion of clusters in a gel while weak concentration fluctuations in the polymer brush decay similarly to a semidilute polymer solution.
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Affiliation(s)
- G E Yakubov
- FORTH/Institute of Electronic Structure and Laser, P.O. Box 1527, 711 10 Heraklion, Crete, Greece
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47
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Michel E, Porte G, Cipelletti L, Appell J. Analysis by the two-fluids model of the dynamical behavior of a viscoelastic fluid probed by dynamic light scattering. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2004; 20:984-990. [PMID: 15773134 DOI: 10.1021/la035678h] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The dynamic properties of a model transient network have been studied by dynamic light scattering. The network is formed by microemulsion droplets linked by telechelic polymers (modified hydrophilic polymers with two grafted hydrophobic stickers). We compare the properties of two networks that are similar but for the residence time of the hydrophobic stickers in the droplets. The results are interpreted according to the so-called two-fluids model, which was initially developed for semidilute polymer solutions and which we extend here to any Maxwellian viscoelastic medium characterized by its elastic modulus and terminal time as measured by rheology. This model is found to describe consistently and quantitatively the experimental observations.
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Affiliation(s)
- Eric Michel
- Groupe de Dynamique des Phases condensees, UMR5581 CNRS-Université Montpellier II, C.C.26, F-34095 Montpellier Cedex 05, France
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48
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Ngai T, Wu C, Chen Y. Effects of Temperature and Swelling on Chain Dynamics during the Sol−Gel Transition. Macromolecules 2004. [DOI: 10.1021/ma030421b] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- To Ngai
- Department of Chemistry, The Chinese University of Hong Kong, Shatin N.T., Hong Kong; The Open Laboratory of Bond Selective Chemistry, Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui, China; and Department of Chemical Engineering, National Cheng Kung University, Taiwan 70101
| | - Chi Wu
- Department of Chemistry, The Chinese University of Hong Kong, Shatin N.T., Hong Kong; The Open Laboratory of Bond Selective Chemistry, Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui, China; and Department of Chemical Engineering, National Cheng Kung University, Taiwan 70101
| | - Yun Chen
- Department of Chemistry, The Chinese University of Hong Kong, Shatin N.T., Hong Kong; The Open Laboratory of Bond Selective Chemistry, Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui, China; and Department of Chemical Engineering, National Cheng Kung University, Taiwan 70101
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49
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Aoki Y, Norisuye T, Tran-Cong-Miyata Q, Nomura S, Sugimoto T. Dynamic Light Scattering Studies on Network Formation of Bridged Polysilsesquioxanes Catalyzed by Polyoxometalates. Macromolecules 2003. [DOI: 10.1021/ma034987b] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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50
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Ngai T, Wu C. Effect of Cross-Linking on Dynamics of Semidilute Copolymer Solutions: Poly(methyl methacrylate-co-7-acryloyloxy-4-methylcoumarin) in Chloroform. Macromolecules 2003. [DOI: 10.1021/ma021580i] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- To Ngai
- Department of Chemistry, The Chinese University of Hong Kong, Shatin. N. T., Hong Kong, and The Open Laboratory of Bond Selective Chemistry, Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui, China
| | - Chi Wu
- Department of Chemistry, The Chinese University of Hong Kong, Shatin. N. T., Hong Kong, and The Open Laboratory of Bond Selective Chemistry, Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui, China
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