Microwave-Assisted In Situ Synthesis of Poly L-Lactic Acid with Nanoparticles of Calcium Phosphate

A microwave reactor was used to polymerize lactic acid and/or calcium lactate in the presence of phosphoric acid or ammonium hydrogen phosphate. The polar nature of lactic acid makes it a strong absorber of microwave radiation, and when present in a nonpolar solvent such as chloroform, it is possible to conduct the polymerization reaction in a microwave reactor. Using calcium lactate and ammonium hydrogen phosphate it is possible to create nanoparticles of calcium phosphate within the matrix of poly lactic acid in situ during the polymerization. FTIR spectroscopy and gel permeation chromatography were used to follow the polymerization process, and transmission electron microscopy was used to determine the size distribution of the calcium phosphate particles.