Oligoethylene-end-capped polylactides

Oligoethylene-end-capped polylactides were synthesized through the ring- opening polymerization of L-lactide with alcohol-terminated oligoethylenes as macro- initiators. The polymerization of L-lactide was carried out in bulk at 130 8C in the presence of stannous octoate and primary alcohols with four different molecular weights: 350, 425, 550, and 700 g/mol. The end-capped copolymers that formed had a number-average molecular weight of approximately 40,000 (weight-average molecular weight/number-average molecular weight ¼ 1.7) according to gel permeation chroma- tography and were highly crystalline in comparison with the similarly formed homo- polymer of L-lactide. The copolymer structure was characterized by Fourier transform infrared, NMR, matrix-assisted laser desorption/ionization time-of-flight mass spec- trometry, and differential scanning calorimetry analysis. This work focused on devel- oping more crystallizable and hydrolytically stable polylactide derivatives that could potentially be used as compatibilizers in polylactide-polyolefin blends or as nucleat- ing agents for poly(L-lactide) or other polyesters. V C 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5257-5266, 2005