DIFFUSION IN AQUEOUS-SOLUTIONS OF POLY(ETHYLENE GLYCOL) AT LOW CONCENTRATIONS

被引:59
作者
WAGGONER, RA
BLUM, FD
LANG, JC
机构
[1] UNIV MISSOURI,DEPT CHEM,ROLLA,MO 65401
[2] UNIV MISSOURI,MAT RES CTR,ROLLA,MO 65401
[3] ALCON LABS INC,FT WORTH,TX 76134
关键词
D O I
10.1021/ma00112a010
中图分类号
O63 [高分子化学(高聚物)];
学科分类号
070305 ; 080501 ; 081704 ;
摘要
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 D2O and in a (1:1) mixture of D2O 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(-alpha), where a ranges from 0.5 for a Theta 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 alpha obtained in D2O at 25 degrees C, D2O at 5 degrees C, and a D2O/diethylene glycol mixture at 25 degrees 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.
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页码:2658 / 2664
页数:7
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