Synthesis of poly(L-lactide) and polyglycolide by ring-opening polymerization.

This protocol describes the synthesis of poly(L-lactide) by ring-opening polymerization of L-lactide using tin(II) 2-ethylhexanoate catalyst as well as the synthesis of polyglycolide by ring-opening polymerization of glycolide. Ring-opening polymerization of cyclic diesters synthesized from alpha-hydroxycarboxylic acids gives high-molecular-weight polyester in high yield. Tin(II) 2-ethylhexanoate catalyst is the most common catalyst for ring-opening polymerization of diesters owing to its high reactivity and low toxicity. Purity of monomers and the amount of water and alcohol in the reaction system are significant factors for increasing molecular weight and conversion of polyesters. The molecular weight of the polyesters is also dependent on reaction temperature and reaction time. This protocol can be completed in 3 d for the synthesis of poly(L-lactide) and 2 d for the synthesis of polyglycolide.