Diffusion in Aqueous Solutions of Poly(ethylene Glycol) at Low Concentrations
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.
R. A. Waggoner et al., "Diffusion in Aqueous Solutions of Poly(ethylene Glycol) at Low Concentrations," Macromolecules, American Chemical Society (ACS), Jan 1995.
The definitive version is available at http://dx.doi.org/10.1021/ma00112a010
Article - Journal
© 1995 American Chemical Society (ACS), All rights reserved.