Functional polymers. IX. Polycarbonates and alternating copolycarbonates of bithionol

A number of polycarbonates, alternating copolycarbonates, polyurethanes, and terpolymers with carbonate and/or urethane linkages utilizing bithionol 2,2'-thiobis(4,6-dichlorophenol)] as the bisphenol component of the polymers have been synthesized. Bithionol has been demonstrated to give a polycarbonate with an inherent viscosity of about 0.5 dl/g. The polycarbonate is amorphous and has a glass transition temperature T_g of about 105°C. Alternating copolycarbonates and polyurethanes involving bithionol are most conveniently prepared from the bischloroformate of bithionol. An alternating copolycarbonate of bithionol and poly(ethylene glycol) of molecular weight 4000 has an inherent viscosity of more than 1.2 dl/g, is water soluble, and has characteristics similar to those of low-density polyethylene. Alternating copolymers of bithionol and other hindered bisphenols have been synthesized and can be visualized as having an antibacterial agent and an antioxidant in the same polymer chain. These polymers have the potential to act as very useful materials for the controlled release of drugs while only forming carbon dioxide as the additional small molecule fragment on hydrolysis.