PROCESS FOR CONTROLLED SYNTHESIS OF POLYLACTIC ACID THROUGH LIVING RING-OPENING POLYMERIZATION OF LACTIDE CATALYSED BY ORGANIC GUANIDINE-NONTOXIC ALCOHOL

摘要

A process for controlled synthesis of polylactic acid through a living ring-opening polymerization reaction of lactide under the catalysis of organic guanidine-nontoxic alcohol as a catalyst. The process adopts a nontoxic organic cyclic guanidine carboxylate as a catalyst and a nontoxic organic alcohol as an initiator, performs the living ring-opening polymerization reaction of lactide by a bulk melt polymerization method, and is characterized in that the catalyst activity is high; the temperature of the polymerization reaction is low; the reaction time is short; the product polymer can be subjected to controlled synthesis within the range of a number-average molecular weight Mn of 0.5×104-5.0×104 according to actual application requirements; the molecular weight distribution of the polymer is narrow (PDI 1.10-1.25); no monomer remains in the polymer (a monomer conversion rate of 100%); and the product is snow-white in colour and the product polymer is high in biological safety.