Microwave-assisted single-step synthesis of poly(lactic acid) by direct polycondensation of lactic acid

The microwave-assisted direct polycondensation of LA to synthesize PLA has been studied. Microwave irradiation strikingly accelerates the polymerization rate of LA compared to conventional heating. By use of a binary catalyst of SnCl2/P-TsOH, PLA with a M, of 16 000 is obtained within 30 min under a reduced pressure of around 30 mmHg. MALDI-TOF MS measurements reveal that the PLA formed is mainly composed of linear polymer and macrocyclics.