Preparation of crystalline and solvent resistant polycarbonates via ring-opening polymerization of cyclic oligomers

A route to solvent-resistant polycarbonates which may also be crystalline has been achieved through the intermediacy of cyclic oligomeric carbonates. Mixed oligomeric cyclics of a variety of bisphenols were prepared via the carefully controlled hydrolysis-condensation of their bischloroformates. Following ring-opening polymerization, the polymers were evaluated for potential solvent resistance. Copolymers of hydroquinone and bisphenol A containing ratios of hydroquinone to BPA between 50/50 and 70/30 were found to be insoluble in CH₂Cl₂, tetrahydrofuran, and CHCl₃, as well as other organic solvents. Polymers containing ratios of hydroquinone/BPA greater than 60/40 show a crystalline melting point by DSC at about 310°C and a glass transition temperature at 154°C.