Structure—property relationships in perfectly alternating segmented polysulphone/poly(dimethylsiloxane) copolymers

Abstract

Well-defined perfectly alternating multiphase segmented polysulphone/poly(dimethylsiloxane) copolymers have been synthesized by the silylamine-hydroxyl coupling reaction and studied by thermal, mechanical and optical scattering methods. The results showed that by varying the length of the segments for each phase and their relative content, it is possible to alter the mechanical and thermal characteristics from those of a thermoplastic elastomer to a tough ductile transparent thermoplastic. The mechanical response was also shown to be influenced according to which phase was predominantly continuous. The evidence of microphase morphology was principally based on dynamic mechanical, small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) measurements. Differential scanning calorimetry (d.s.c.) scans showed the breadth of the high temperature transitions to span up to 60°C, reflecting the polydisperse nature of both oligomers. New results from SAXS analysis agree well with TEM measurements and indicate that the interfacial thickness parameter and degree of phase separation also show a composition and block length dependency for these copolymers. The interfacial thickness parameter, based on Koberstein's empirical method, was found to vary from 0.8 to 1.3 nm, depending on the composition.