Preparation of Propargyl-terminated Polylactide by the Bulk Ring-opening Polymerization

Propargyl-terminated polylactide was prepared by bulk ring-opening polymerization of L-lactide (LLA) at 105 degrees C in the presence of 3-methyl-1-pentyn-3-ol as the initiator and Sn(Oct)2 as the catalyst. A significant decline of the alkynes chain-end functionality was observed by 1H NMR even at the early stage of the polymerization. The most probable reason is the intermolecular oxidative coupling of the propargyl end groups. Propargyl-terminated polylactide having higher chain-end functionality (f = 86%) and low polydispersity (PDI = 1.22) was prepared with the addition of N,N,N',N'',N''-pentamethyldiethylenetriamine, whose huge steric hindrance provides the protective effect of propargyl groups.