Polymer-polymer interactions in dilute solution

Cotts, Patricia M.; Selser, J. C.

doi:10.1021/ma00209a029

Cited by 43 publications

(73 citation statements)

References 18 publications

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“…15 In the present case, DME solvent quality is best classified as marginal since the measured k D φ values all lie well within the best estimate of the Θ condition (k D φ ) -2) 7 and the limit expected for good solvents (k D φ = 2). 7 The relatively weak variation in DME solvent quality with pressure or density is reflected in the essentially constant values of the hydrodynamic radius. Interestingly, unlike the case for PEB 10 -alkane solutions, 15 sub-Θ solubilization of PEB 10 in DME is not observed; that is, the lowpressure phase separation of PEB 10 -DME solutions occurs upon approach to the Θ condition without a rapid decrease in k D φ and without a concomitant decrease in R H .…”

Section: Resultsmentioning

confidence: 99%

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Density-Induced Phase Separation in Poly(ethylene-co-1-butene)−Dimethyl Ether Solutions

McHugh

Zanten

2005

Macromolecules

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Dynamic light scattering measurements are reported for poly(ethylene-co-20.2 mol % 1-butene) (PEB10) in dimethyl ether (DME) at 110-170°C and pressures to 2500 bar. The cloud-point curve for the PEB10-DME system exhibits both low-and high-pressure upper consolute solution temperature (UCST) branches. The polymer infinite dilution translational diffusion coefficient, D0, increases with increasing temperature and decreasing pressure as expected. The observed variation of D0 is inversely proportional to the solvent viscosity, indicating that the polymer coil hydrodynamic size is independent of temperature and pressure. The dynamic second virial coefficient, kD, which represents a balance between thermodynamic interactions and hydrodynamic forces, displays values that lie within the bounds expected for Θ and good solvent conditions. While the low-pressure UCST is classical in that the polymer-solvent interactions become unfavorable upon approach to this phase boundary, the highpressure UCST branch exhibits anomalous behavior wherein polymer-solvent interactions improve as this phase boundary is approached. Such behavior suggests that the phase separation is entropic in origin and is driven by unfavorable mixing effects.

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Section: Resultsmentioning

confidence: 99%

“…This observation is unlike the behavior observed upon approach to the low-pressure UCST in the present case and to liquid-liquid phase boundaries in other systems where k D was observed to decrease. 7,15,17 Upon approach to the high-pressure UCST, k D continually increases and, therefore, A 2 also increases since 7…”

Section: Resultsmentioning

confidence: 99%

Density-Induced Phase Separation in Poly(ethylene-co-1-butene)−Dimethyl Ether Solutions

McHugh

Zanten

2005

Macromolecules

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“…φ* ) 3M w /(4πFN A R g 3 ) is the overlap volume fraction, M w the weight-averaged molecular weight, R g the radius of gyration (〈R e 2 〉 ) 6〈R g 2 〉), F the density, and N A the Avogadro number. At low momentum transfers neutron and light scattering access the collective diffusion coefficient D(φ) 16,17 with A 2 the second virial coefficient, V w the polymer volume, and D 0…”

Section: Theoretical Considerationsmentioning

confidence: 99%

Origin of Internal Viscosity Effects in Flexible Polymers: A Comparative Neutron Spin-Echo and Light Scattering Study on Poly(dimethylsiloxane) and Polyisobutylene

et al. 2001

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We present a comparative neutron spin-echo and dynamic light scattering study of the chain dynamics of the dynamically very flexible poly(dimethylsiloxane) (PDMS) with the orientationally hindered polyisobutylene (PIB). Both polymers exhibit the same static rigidity. In the melt PDMS follows the Rouse dynamics up to momentum transfers of Q ) 0.4 Å -1 , while PIB displays a strong influence of local dynamics already above Q ) 0.15 Å -1 . In dilute solution the dynamic structure factors and the diffusion coefficients of both polymers were studied over a wide temperature and Q range. A comparative evaluation of the PIB intrachain dynamics on the basis of PDMS results, which are taken to reflect as in the melt "ideal" relaxations, shows that intrachain viscosity effects are the leading mechanism displayed by the Rouse and Zimm models. The characteristic relaxation time of the intrachain viscosity τ 0 agrees well with the rotational barriers in PIB, corroborating the underlying physical idea of a delayed redistribution of conformational states to be at the origin of internal viscosity effects.

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“…27 This data treatment neglects the formation of rings, which cer- (4) Poly(R-methylstyrene) in the marginal solvent cyclohexane at 50°C and in the good solvent toluene. 35 The lines correspond to expressions by Cotts 35 and Akcasu, 36 respectively. a Mw(c) in 10 3 g/mol from SLS derived previously, 1 Dc in 10 -7 cm 2 /s from DLS, kD(c) in mL/g according to Mw(c), Dz°(c) in 10 -7 cm 2 /s after correction with kD(c).…”

Section: Coupling Of Amino-terminated Polystyrenesmentioning

confidence: 98%

“…Molecular weight dependence of the kD parameter of linear polymers: (9, 2, 1) amino-terminated PS; (0) linear PS in toluene; 32 (b) poly(R-methylystyrene) in toluene 35. The lines correspond to eqs 11 and 12.k D ) 3.26 × 10 -4 M 0.95 [mL/g], M w > 30 × 10 3 (11) k D ) 7.16 × 10 -6 M w 1.32 [mL/g], M w < 30 × 10 3 (12)…”

mentioning

confidence: 99%

Association of Amino-Terminated Polystyrenes. 2. Dynamic Light Scattering of Associating Linear Chains

Merkle¹,

Burchard²

1996

Macromolecules

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Dynamic light scattering was used to study the associating coupling process of aminoterminated polystyrene chains with monofunctional and bifunctional dinitrophenol reagents. The tertiary amino end group and the end group which results from association with monofunctional dinitrophenol were found to have no effect on the solution behavior in good solvents. The interaction with the coupling reagent caused a decrease in the mutual diffusion coefficients Dc with increasing polymer concentration. Translational diffusion coefficients Dz°(c) of the associating polymers at each concentration c with a corresponding molecular weight Mw(c) were determined from Dc and its concentration dependence which is expressed by the kD parameter. The molecular weight dependence of the kD parameter was obtained from experimental values of linear polystyrenes in toluene. On the time scale of these experiments, the associates were found to show a diffusion behavior that corresponds to covalently linked chains. Apparently the lifetime of a complex is longer than the measurement time in typical experiments.

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Polymer-polymer interactions in dilute solution

Cited by 43 publications

References 18 publications

Density-Induced Phase Separation in Poly(ethylene-co-1-butene)−Dimethyl Ether Solutions

Density-Induced Phase Separation in Poly(ethylene-co-1-butene)−Dimethyl Ether Solutions

Origin of Internal Viscosity Effects in Flexible Polymers: A Comparative Neutron Spin-Echo and Light Scattering Study on Poly(dimethylsiloxane) and Polyisobutylene

Association of Amino-Terminated Polystyrenes. 2. Dynamic Light Scattering of Associating Linear Chains

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