Static and dynamic behavior of semidilute polymer solutions

Brown, Wyn; Nicolai, Taco

doi:10.1007/bf01410586

Cited by 126 publications

(174 citation statements)

References 81 publications

(87 reference statements)

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“…(the semidilute crossover is, however, broad and solutions display semidilute properties across this range 33,40 ). We conclude, similarly to the dilute regime, that the polymer conformation in the semidilute regime remains unchanged below and above c C 60 tol .…”

Section: Resultsmentioning

confidence: 99%

Conformation and Interactions of Polystyrene and Fullerenes in Dilute to Semidilute Solutions

Dattani¹,

Michels

Nedoma³

et al. 2014

Macromolecules

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We report the polymer conformation and fullerene aggregation in a ternary system containing polystyrene, C 60 and toluene measured by small angle neutron, static and dynamic light scattering. We investigate polymer concentrations across the dilute and semidilute regime for five polymer molecular weights (M w =20k-1Mg/mol), and fullerene concentrations below and above its miscibility threshold in toluene.We find that the polymer radius of gyration (R poly g ), hydrodynamic radius (R h ) * To whom correspondence should be addressed † Centre for Plastic Electronics, Imperial College London, London, SW7 2AZ, United Kingdom ‡ Department of Chemical Engineering, Imperial College London, London, SW7 2AZ, United Kingdom ¶ Physikalische Chemie, Universität Paderborn, 33098 Paderborn, Germany § Institut Laue-Langevin, DS/LSS, F-38 042 Grenoble, France Materials Department, Imperial College London, London, SW7 2AZ, United Kingdom 1 and the mixture correlation length (ξ) remain unchanged upon addition of C 60 .The miscibility of C 60 in toluene, however, decreases upon addition of polystyrene forming aggregates with a time-dependent radius on the order of 100 nm, and this effect is amplified with increasing polymer M w . Our findings are relevant to the solution processing of organic photovoltaics, which generally require the effective solubilisation of fullerene derivatives and polymer pairs in this concentration range.

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Section: Resultsmentioning

confidence: 99%

Conformation and Interactions of Polystyrene and Fullerenes in Dilute to Semidilute Solutions

Dattani¹,

Michels

Nedoma³

et al. 2014

Macromolecules

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“…The difference of C* calculated based on these definitions could be as large as five times. 112,113 On the other hand, at the entanglement concentration (C e ), polymer chains start to interwind with each other, where C e can be estimated from the ratio of the chain length (L) and the entanglement length (L e ). 114 C e is higher than C*.…”

Section: Llsmentioning

confidence: 99%

The slow relaxation mode: from solutions to gel networks

Ngai

2010

Polym J

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In the past, many laser light-scattering experimental results revealed that besides the fast relaxation mode, there existed an additional slow mode in semidilute solutions. This slow mode has been assigned to a variety of origins, but there has been no clear and well-accepted explanation. As the polymer concentration increases, the slow relaxation mode persists in the concentrated region, in melts and in gels in which polymer chains are crosslinked instead of entangled. The slow relaxation mode has also been reported for charged macromolecules in aqueous and nonaqueous solutions. However, it is generally thought to be different in nature from that observed in semidilute neutral polymer solution. In recent years, armed with novel solution preparation methods and some specially designed polymers, we have reexamined the dynamics of polymer chains, especially the slow mode, in semidilute neutral polymer solutions, dilute polyelectrolyte solutions and gels, which are reviewed here. Our results suggest that the slow mode can be qualitatively considered as hindered motions of interacting chains even though the nature of interaction can be very different; namely, from the weak segment-segment interaction in a less good solvent to strong electrostatic interaction among polyelectrolyte chains, and even to chemical crosslinking inside gel networks.

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“…50 The density screening length has been measured for only a few polymers, and up to Φ ≈ 0.3-0.4 at best. For polystyrene, the average of many experiments yields 47 F ≈ 2.5 Å Φ -0.72 (good solvents) and…”

Section: Estimates Of Parametersmentioning

confidence: 99%

“…Further, the temporal decay of the matrix constraints during the disentanglement step of the matrix, see eqs I. 47 and I. 48, is considered self-consistently; this process is termed "constraint release mechanism" and provides another parallel channel for the relaxation of the constraining excluded volume forces.…”

Section: Introductionmentioning

confidence: 99%

Polymer-Mode-Coupling Theory of Finite-Size-Fluctuation Effects in Entangled Solutions, Melts, and Gels. 2. Comparison with Experiment

Fuchs

Schweizer

1997

Macromolecules

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The predictions of polymer mode coupling theory for the finite size corrections to the transport coefficients of entangled polymeric systems are tested in comparison with various experimental data. It is found that quantitative descriptions of the viscosities, η, dielectric relaxation time, τ , and diffusion coefficients, D, of polymer melts can be achieved with two microscopic structural fit parameters whose values are in the range expected from independent theoretical or experimental information. An explanation for the (apparent) power law behaviors of η, τ , and D in (chemically distinct) melts for intermediate molecular weights as arising from finite size corrections, mainly the self-consistent constraint release mechanism, is given. The variation of tracer dielectric relaxation times from Rouse to reptationlike behavior upon changes of the matrix molecular weight is analyzed. Self-diffusion and tracer diffusion constants of entangled polymer solutions can be explained as well, if one further parameter of the theory is adjusted. The anomalous scaling of the tracer diffusion coefficients in semidilute and concentrated polystyrene solutions, D ∼ N -2.5 , is predicted to arise due to the spatial correlations of the entanglement constraints, termed "constraint porosity". Extensions of the theory to polymer tracer diffusion through poly(vinyl methyl ether) and polyacrylamide gels provide an explanation of the observation of anomalously high molecular weight scaling exponents in a range where the size of the tracer, Rg, already considerably exceeds the gel pore size, g. IntroductionThe microscopic polymer mode coupling (PMC) theory connects the dynamics of entangled polymeric systems to the underlying equilibrium liquid structure. This description therefore naturally includes corrections arising from the finite molecular weights of tracer or matrix polymers. In the preceding paper, 1 referred to as paper I, the PMC predictions with finite size corrections have been worked out for the transport properties of entangled solutions and melts and for polymer tracer motion in gels. In the present paper these results are compared with data from many experiments. As the PMC approach has been detailed in the preceding paper, 1 it shall be summarized only shortly in this section and then compared to alternative approaches. The resulting formulas of paper I will be referenced by the equation numbers of that paper with a prefix I.The PMC approach of paper I treats the Rouseentangled crossover problem in a simple interpolative manner. The PMC contributions capturing the entanglement corrections are combined with the Rouse, unentangled quantities, see eqs I.52 and I.68 for D, eqs I.55 and I.67 for η, and eqs I.58 and I.70 for τ . Appreciable deviations from the asymptotes for high molecular weights are therefore not explained by corrections of the Rouse dynamics to the asymptotic, entangled motion. In stark contrast to the contour length fluctuation model of Doi, 2,3 the repton model of Rubinstein, 4 and the Rouse-fluc...

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Static and dynamic behavior of semidilute polymer solutions

Cited by 126 publications

References 81 publications

Conformation and Interactions of Polystyrene and Fullerenes in Dilute to Semidilute Solutions

Conformation and Interactions of Polystyrene and Fullerenes in Dilute to Semidilute Solutions

The slow relaxation mode: from solutions to gel networks

Polymer-Mode-Coupling Theory of Finite-Size-Fluctuation Effects in Entangled Solutions, Melts, and Gels. 2. Comparison with Experiment

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