Title

Diffusion in Aqueous Solutions of Poly(ethylene Glycol) at Low Concentrations

Abstract

We have observed the scaling behavior of the diffusion coefficient of poly(ethylene glycol) (PEG) ranging from dimer to n-mer of 14 000 ethylene glycol units in D 2O and in a (1:1) mixture of D 2O and diethylene glycol, solvents of both low and moderate viscosities. The accepted scaling relationship for diffusion of polymers at infinite dilution is D 0 = KM -a, where a ranges from 0.5 for a Θ solvent to 0.6 for a good solvent, as originally proposed by Flory. Measuring D 0 as the extrapolated value of D versus concentration in a PGSE-NMR experiment, we find a surprisingly good fit to this scaling relationship over the entire molecular weight range for both solvent systems. The values of a obtained in D 2O at 25 °C, D 2O at 5°C, and a D 2O/diethylene glycol mixture at 25°C were 0.597 ± 0.020, 0.534 ± 0.021, and 0.542 ± 0.058, respectively. The extension of the scaling behavior down to the dimer species is believed to be due to the high local segmental friction coefficient of the ethylene oxide unit. © 1995 American Chemical Society.

Department(s)

Chemistry

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 1995 American Chemical Society (ACS), All rights reserved.


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