Dynamics of Water in a Polymer Matrix Studied by a Microwave Dielectric Measurement

Abstract

Dielectric measurements on water mixtures of polymers such as poly(vinylpyrrolidone) (PVP), poly(ethylene glycol) (PEG), poly(vinyl methyl ether) (PVME), poly(vinyl alcohol) (PVA), poly(acrylic acid) (PAA), poly(ethylenimine) (PEI), and poly(allylamine) (PAlA) were performed over a frequency range from 300 MHz to 15 GHz at 25 °C. Dielectric dispersion and absorption curves related to the orientational motion of water can be described well by the Cole−Cole equation. The distribution of the relaxation time is interpreted by the variation of the water structure. The logarithmic plot of the relaxation time against the parameter for the distribution of the relaxation time suggests two groups of polymers. One group contains nonelectrolyte polymers and another contains electrolyte polymers and PVA. This result implies that water structures in the mixtures of the former group are more uniform and stable than that in the mixtures of the latter group.