Sorption and Diffusion Behavior of Styrene-Butadiene Block Copolymers

摘要

Transport properties of multi-phase polymers are generally affected by the variations in morphology and molecular structure. Information provided by sorption or permeation data, however, are difficult to relate to the structure of these polymers. A substantial amount of work has been done in the area of organic vapor sorption in styrene-butadiene block copolymers consisting of glassy polystyrene (PS) domains dispersed in a rubbery poly-butadiene (PB) matrix (1-4). In studies by Odani et.al. (1) and Chiang and Sefton (2), non-Fickian sorption behavior for SBS block polymer films was attributed to a solvent induced relaxation of the interphase region between the PS domains and PB matrix. In the authors recent work (4), solute transport, in a composite of slowly permeable spherical domains dispersed uniformly throughout a rapidly permeable matrix, was simulated via a mathematical model. The model showed that non-Fickian sorption could occur without relaxation, but was dependent on, among other things, volume fraction and size of dispersed glassy phase, and film thickness. The purpose of the paper is to study, in detail, the sorption and diffusion behavior of several SB block copolymers and to attempt to correlate these data to the morphology of the polymers.