New Route to Segmental Star-Shaped Copolymers of Lactic Acid

Abstract

The star-like copolymers containing polylactide core and poly(propylene maleate) arms have been synthesized in two steps. The polylactide segments of M_n in the range 1000–8500 terminated either by OH or COOH functional groups were prepared by melt condensation of L-lactic acid in the presence of pentaerythritol, or 1,2,3,4-butanetetracarboxylic acid. Selected products were applied as coinitiators and chain transfer agents in the copolymerization of maleic anhydride with propylene oxide catalyzed by magnesium ethoxide or metal salen complexes. Four-arm stars of M_w in the range 11000–35000 have been prepared. Thermal analysis revealed a lower T_g for the copolymers compared to polylactide core.

Keywords:

• Cyclic anhydrides
• epoxides
• lactic acid copolymers
• segmental polyesters
• star polymers

Acknowledgments

This work was carried out within the project co-financed by the European Union–European Regional Development Fund under Operation Program Innovative Economy–BIOPOL POIG.01.01.02-10-025/09 “Technology of preparation of biodegradable polyesters from renewable resources.”