Influence of associations on self-diffusion of styrene-methylmethacrylate random copolymers in semidilute acetone solution

Fleischer, G.; Rittig, Frank; Koňák, Čestmı́r

doi:10.1002/(sici)1099-0488(19981130)36:16<2931::aid-polb8>3.0.co;2-n

Cited by 12 publications

(9 citation statements)

References 23 publications

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“…The high values of σ in the semidilute regime cannot be accounted for by a high polydispersity in molecular weight, since the values of σ are much lower at high SDS concentration and in dilute polymer solutions. A broad distribution (curvature) has previously been attributed to a combined effect of polydispersity in molecular weight and associations of the polymer chains. , Furthermore, a strong scaling of the molecular weight on the diffusion coefficient is expected when the polymer chains diffuses in a static, heterogeneous matrix. , In fact, by a previous study, performed by DLS on the same systems, we were able to determine the heterogeneity of the systems . The result is that the systems are most heterogeneous in the region where we observe the increase and maximum in σ and the viscosity of the HM-EHEC polymers.…”

Section: Resultssupporting

confidence: 56%

“…A broad distribution (curvature) has previously been attributed to a combined effect of polydispersity in molecular weight and associations of the polymer chains. 21,38 Furthermore, a strong scaling of the molecular weight on the diffusion coefficient is expected when the polymer chains diffuses in a static, heterogeneous matrix. 39,40 In fact, by a previous study, performed by DLS on the same systems, we were able to determine the heterogeneity of the systems.…”

Section: Resultsmentioning

confidence: 99%

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Associations in Mixtures of Hydrophobically Modified Polymer and Surfactant in Dilute and Semidilute Aqueous Solutions. A Rheology and PFG NMR Self-Diffusion Investigation

et al. 2000

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Viscosity (dilute regime) and surfactant and polymer NMR self-diffusion (dilute and semidilute regime) measurements were carried out on aqueous solutions of ethyl(hydroxyethyl)cellulose (EHEC) and of a hydrophobically modified analogue, with (HM4-EHEC) and without (HM0-EHEC) a spacer, in the presence of various amounts of sodium dodecyl sulfate (SDS). Strong polymer-surfactant interactions were revealed. From the binding isotherm the critical aggregation concentration (cac ≈ 3 mm) was obtained for the EHEC/SDS system. By comparing the results from the binding isotherms with those from the rheological measurements, molecular interactions could be correlated to macroscopic properties. The polymer self-diffusion results suggest that the spin-echo attenuation can be described by a log-normal distribution (distribution of self-diffusion coefficients), giving a median polymer self-diffusion coefficient D ME. There is no difference in the trend of DME between EHEC and the hydrophobically modified analogues at various SDS concentrations. The NMR signal decays of highly viscous samples of the modified analogues are initially described by a distribution mode followed by a single exponential (slow component). The effect of hydrophobic modification is seen in the existence of a slowly diffusing component (Dnet ≈ 10 -14 m 2 s -1 ) (not observed for the unmodified analogue) that is related to a strong and long-lived network, at least of the order of the NMR time scale (ca. 0.5 s).

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Section: Resultssupporting

confidence: 56%

Section: Resultsmentioning

confidence: 99%

Associations in Mixtures of Hydrophobically Modified Polymer and Surfactant in Dilute and Semidilute Aqueous Solutions. A Rheology and PFG NMR Self-Diffusion Investigation

et al. 2000

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“…He et al 21,22 studied the physical gelation of a multiblock copolymer poly(dimethylsiloxane)-poly[1-(dimethylsilyl)-4-[(dimethylvinyl)silyl]benzene]) and the effect of copolymer composition (content) and solvent type. Konak et al 23 and Fleischer et al 24 found random associations also existed in a solution of styrene-methylmethacrylate random copolymer in the polymethylmethacrylate selective solvent (acetone), and suggested that such random association should exist even in solutions of statistical copolymers in selective nonaqueous solvents.…”

Section: Rheological Propertiesmentioning

confidence: 99%

Structure formation in injectable poly(lactide‐co‐glycolide) depots. II. Nature of the gel

et al. 2004

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The benzyl benzoate solutions of poly(D,L-lactide-co-glycolide), a random oriented synthesized copolymer with L/G ratio of 50:50, have been shown to form gels during aging and upon injection into buffer or water. The gelation properties influence drug release kinetics for these injectable, depot-forming solutions. In this article, we report on the mechanism of gelation. We find that only polymers that have a certain average block length of glycolide units form gels during aging as well as depots upon in vitro. Thus, gel formation is likely due to the formation of ordered solvated aggregates of blocky glycolide units. Rheometry, differential scanning calorimetry, and nuclear magnetic resonance were used to investigate the gelation kinetics and the polymer molecular parameters. Of all the polymers used, poly(lactide-coglycolide)s with glycolide average block length <2.9 did not show any gelation behavior. The details of the gelation process are also solvent dependent.

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“…If clusters and/or a distribution of self-diffusivities are present, S inc ( q,t ) deviates from single-exponential behavior. The influence of cluster formation on S inc ( q,t ) was recently demonstrated in solutions of a random copolymer of styrene and methyl methacrylate dissolved in acetone, a bad solvent for styrene …”

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confidence: 99%

Self-Diffusion in Concentrated Solutions of Polystyrene in Toluene: No Evidence for Large-Scale Heterogeneities

Fleischer

1999

Macromolecules

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Influence of associations on self-diffusion of styrene-methylmethacrylate random copolymers in semidilute acetone solution

Cited by 12 publications

References 23 publications

Associations in Mixtures of Hydrophobically Modified Polymer and Surfactant in Dilute and Semidilute Aqueous Solutions. A Rheology and PFG NMR Self-Diffusion Investigation

Associations in Mixtures of Hydrophobically Modified Polymer and Surfactant in Dilute and Semidilute Aqueous Solutions. A Rheology and PFG NMR Self-Diffusion Investigation

Structure formation in injectable poly(lactide‐co‐glycolide) depots. II. Nature of the gel

Self-Diffusion in Concentrated Solutions of Polystyrene in Toluene: No Evidence for Large-Scale Heterogeneities

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