Swelling behavior of bisphenol-a polycarbonate-polyoxyethylene multiblock copolymers in ethanol/water mixtures

Abstract

Swelling behavior was investigated on randomly-coupled (AB)n-type multiblock copolymers of bisphenol-A polycarbonate (PC) and polyoxyethylene (POE) in ethanol/water mixtures of various composition. The degree of swelling, Qw, defined as the weight ratio of the swollen and dry films, was dependent not only on PC/POE composition and block length but also on the sample’s history. As-cast specimens of the samples having 70 wt% POE content showed a high maximum in the Qw vs solvent composition curve at an ethanol content close to the azeotropic composition. This maximum disappeared by annealing and/or ethanol-conditioning the as-cast films. The swelling behavior of these conditioned films was similar to that of crosslinked POE gels. In the copolymers investigated, hydrophobic PC microdomains may act as physical crosslinks for the hydrophilic POE gel phase. Thus, as-cast specimens may have a large sorptive capacity because of imperfect microphase separation and a resulting loose quasi-network structure. © 1984 The Society of Polymer Science, Japan.