Effect of Molecular Weight on the Mutual Diffusion Process in Polystyrene/Poly(Vinyl Methyl Ether) System

Abstract

Attenuated Total Reflection (ATR) spectroscopy was used to study the interdiffusion mechanism at the interface of Polystyrene (PS) and Poly(vinyl methyl ether) (PVME), at temperatures above and below the glass transition temperature (Tg) of PS, but in the miscible region. One molecular weight of PVME and 13 molecular weights of PS, both below and above the critical molecular weights of PS were used to investigate the effect of molecular weight on mutual diffusion process both below and above the critical molecular weight for entanglements of PS. To extract the diffusion coefficient from experimental data, we used the approach suggested by Jabbari and Pepas. Both Fickian and Case-II diffusion were necessary to fit the PVME concentration profile for the various molecular weights. The experimental results were also compared with the slow-mode and the fast mode theories2-3.