Ring-Opening Polymerization of Lactide Using Microwave and Conventional Heating

The ring-opening polymerization (ROP) of lactide has been done in two ways: microwave heating and conventional heating. The ROP has been successfully carried out with various initiators by the conventional method. Experiments were carried out using a wide range of monomer to initiator ratio. Polymerization reactions were carried out in two different environments in the reaction vessel, an inert gas cover and partial vacuum. The polymerization rate is much faster in microwave heating than that in conventional heating. It is shown that the procedure of dispersion of the catalyst in polymerization system affects the molar mass distribution of the product as is evidenced by the bimodality observed in the SEC chromatograms. Poly (lactic acid) was synthesized by microwave irradiation catalyzed by stannous octoate (SnOct2) under vacuum. The molecular weight has been determined by viscometry and GPC.