EFFECT OF POLYMERIZATION CATALYSTS ON THE MICROSTRUCTURE OF P(LLA-CO-EPSILON-CL)

The copolymerization of L,L-lactide and epsilon-caprolactone was carri ed out using antimony trioxide and stannous octoate as catalysts. The effect of polymerization catalysts on the physical and the chemical mi crostructures of this copolymer was investigated by C-13 NMR and DSC a nalysis. Antimony trioxide causes more random sequence distribution wi thin the copolymer chain due to its higher transesterification charact eristic than stannous octoate. The copolymer samples made with the ant imony trioxide catalyst seem to have more amorphous phase structure, t han those prepared using stannous octoate which are semicrystalline fo r the entire compositional range due to blocky copolymer sequences. (C ) 1994 John Wiley and Sons, Inc.