Block copolymers based on 2,2‐bis(4‐hydroxyphenyl)propane polycarbonate. II. Effect of block length and composition on physical properties

Block copolymers of 2,2‐bis(4‐hydroxyphenyl)propane (BPA) polycarbonate and poly(ethylene oxide) (PEG) were used in a study of the influence of composition and block size on the thermal and mechanical properties of block copolymers. By copolymerizing polycarbonates of controlled molecular weight with similarly characterized poly(ethylene oxide) glycols, it was found feasible to alter the size of each type of block independently of the other. To complement this investigation, the effect of varying the concentration of a compatible plasticizer on the physical properties of the BPA polycarbonate was also studied. The BPA polycarbonate was rendered thermally crystallizable and flexible either by the copolymerization with PEG or by the addition of low molecular weight plasticizer. Degradation of tensile modulus and strength was observed with increased PEG content but was less for the copolymers with the longer blocks.