Liquid PEG4-PLLA copolymers: Effect of chirality and molecular weight on mechanical properties

The mechanical properties of polylactic acid (PLA), largely determined by its molecular weight and tacticity, can be modified by copolymerization and multi-armed structure, among other things. A series of liquid PEG(4)-PLA copolymers bearing various PDLLA or PLLA of increasing molecular weights was synthesized and characterized. The glass transition temperature and viscosity gradually increased with the molecular weight and the optical purity of the copolymer's PLA segment. The release profiles of two model drugs, bupivacaine HCl and bovine serum albumin were comparable, and controlled by the molecular weight and dissolution of the polymeric carrier. These findings can help in the development of new applications in biomedicine in which viscosity plays a significant role.