Bisphenol‐A‐polycarbonate‐bisphenol‐A‐polysulfone block copolymers

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Abstract
Multiblock , block copolymers of bisphenol‐A‐polycarbon ate and bisphenol‐A‐polysulfone were prepared by three different synthesis routes. The in situ method consisted of forming the polycarbonate block in the presence of hydroxyl terminated polysulfone oligorner. The coupled oligomer technique utilized phosgene to link up the two preformed oligomers to high molecular weight. In one case, a perfectly alternating block copolymer was formed by reacting a ∼9, 000 Mn chloroformate terminated polycarbonate with a ∼9, 000 Mn hydroxyl terminated polysulfone. Block sizes from ∼4, 000 to ∼26, 000 were investigated. The oligomers and copolymers were characterized by potentiometric titrations and UV end group analysis. Membrane osmometry and gel permeation chromatography were also employed. Dynamic mechanical behavior of solvent cast and compression molded films was assessed via rheovibron measurements. The copolymers were ductile and transparent and displayed essentially only a single intermediate glass transition temperature, that is, microphase separation was not observed. This is in contrast to simple physical blends of the homopolymers or oligomers, which are opaque and display two glass transition temperatures.

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