Ring opening polymerization of poly(L-lactide) by macroinitiator

1-dodecanol and other alcohols have been used as initiators for ring opening polymerization of poly(L-lactide) (PLLA) from L-lactide monomers. These initiators are liquid and can evaporate during reaction, which affects yield and polymer molecular weight. We describe synthesis of PLLA from L-lactide initiated by a macroinitiator, poly(butylene succinate (PBS), with stannous octoate as catalyst. PBS is miscible with the lactide and enhances the efficiency of ring opening polymerization. The optimum mole ratio of PBS, temperature and recation time were determined. The chemical structure of the synthesised PLLAs were verified by NMR. Differential scanning calorimetry indicated that 0.001 mol% PBS led to the highest melting temperature ∼164 °C and melting enthalpy 74 J/g. Gel permeation chromatography showed that polymerization at 160°C for 4 hours led to the highest molecular weight about 24000 g/mol and 84% PLLA yield. In contrast, in similar conditions polymerization, 0.1 mol% of 1-dodecanol, produced alower molecular weight 6,200 g/mol and 65% yield.