Copolymerization of L-Lactide and ε-Caprolactone promoted by zinc complexes with phosphorus based ligands

The zinc complexes 1 and 2 bearing chelating phosphorous based pincer ligands were found to catalyze the ring-opening copolymerization of L-lactide and epsilon-caprolactone in the melt at 110 degrees C to obtain a series of random copolymers in which the monomer distributions were coherent with the monomer ratio in the feed. All the obtained copolymers showed high molecular masses with monomodal and moderately narrow distributions. The thermal properties of the achieved copolymers (T-g, glass transition temperature, and T-m, melting temperature) were strongly dependent on their composition. A linear dependence of T-g with molar percentage of lactide in the copolymers was observed over a temperature range from -59 degrees C (pure polycaprolactone) to 55 degrees C (pure polylactide).

Automated summary

The zinc complexes with chelating phosphorous based pincer ligands were found to catalyze the ring-opening copolymerization of L-lactide and epsilon-caprolactone in the melt, resulting in high molecular weight copolymers with thermal properties strongly dependent on their composition.