Microwave Synthesis of Poly(L-lactic acid)

Synthesis of poly(L-lactic acid) typically requires a long process time with the use of tin octoate as a catalyst. In this study microwave-assisted polymerization of lactic acid has been studied both with the aid and without the aid of tin octoate catalyst. While the presence of tin octoate assists in the polymerization process, it is not a pre-requisite to polymerization with microwaves. Molecular masses in excess of 25 kDa were possible over process times as little as 2.5 h without the need for a controlled environment. Fourier-transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy and gel-permeation chromatography were used to follow the polymerization process. Microwave-assisted polymerization of lactic acid to yield poly(L-lactic acid) has been shown to be a viable and quicker alternative to tradition approaches to the synthesis of poly(L-lactic acid).