Diffusion of poly(ethylene oxide) in semidilute aqueous solution: Dynamic light scattering and gradient diffusion

Gradient diffusion measurements and dynamic light scattering data are presented for semidilute aqueous solutions of narrow distribution (molecular weight M: 2.5 × 10⁴ – 1.2 × 10⁶) poly(ethylene oxide) fractions. Resolution of the time correlation function using bimodal analysis gave: (a) a fast mode, identical within experimental error to the classical gradient diffusion values; (b) a slow mode, interpreted as reflecting the translational motions of clusters of entangled chains. The results are similar to those found for other aqueous polymer systems, probably reflecting the ease with which association occurs between extended, polar, chains.