ROLE OF MOLECULAR ARCHITECTURE IN POLYMER DIFFUSION - A PGSE-NMR STUDY OF LINEAR AND CYCLIC POLY(ETHYLENE OXIDE)

The concentration dependence of the self-diffusion coefficient of mono disperse poly(ethylene oxide) (PEG) dissolved in deuterated water has been measured for three polymer samples. Two samples have the same nom inal molecular weight M(n) approximate to 10000 but differ in molecula r architecture-linear and cyclic-while the third is a smaller, linear sample for comparison. The concentration behavior of the self-diffusio n coefficient for the cyclic sample suggests a much smaller hydrodynam ic radius compared to the linear sample of equivalent molecular weight . From a comparison of the two linear samples, an estimate of the ''eq uivalent linear'' molecular weight of the cyclic polymer can be obtain ed.