Synthesis and post-polymerization modification of polyester containing pendant thiolactone units

A simple and an efficient approach has been developed for the synthesis of polyesters containing pendant thiolactone units. For this purpose, polyester P1 possessing electron deficient triple bonds in the main backbone was prepared, and subsequently reacted with benzyl-azide and thiolactone-azide (TLa-N-3) at a mole ratio of 2:1 (per alkyne), through the metal-free azide-alkyne cycloaddition reaction in N,N-dimethylformamide (DMF). The resulting polymer, P2, was then subjected to aminolysis reactions by using various primary amines with different amounts depending on the amine structure, in the presence of methyl acrylate (1.5 fold per amine) to capture, in situ, formed thiol during the reactions, by means of thiol-Michael addition reaction. The resulting polymers have been characterized by GPC, NMR, and DSC.