Microwave assisted synthesis of biodegradable polymers, blends and composites: Potentials for drug delivery and orthopedic applications

The present study focuses on using this novel heating technology to carryout highly energy intensive polymerization process. L-lactic acid polymerization was carried out under microwave heating. High molecular weight poly (l-lactic acid) was synthesized with or without using Sn-octoate catalyst. Polymerization time was reduced to a few hours under microwave heating compared to 24 to 48 hours required by conventional polymerization process. Increase in the reaction rates were attributed to both thermal and non thermal heating effects of microwave. Copolymeric blend of immiscible polymers like PLLA and PGA were also prepared using microwave heating, resulting in blends which exhibited uniformity, block copolymerization and good compatibility. Insitu synthesis of hydroxyapatite during lactic acid polymerization under microwave heating resulted in high molecular weight PLLA with nano to micron scale hydroxyapatite particles embedded in the matrix. Degradation of low molecular weight microwave synthesized PLLA showed bulk degradation and have been shown as potentials for drug delivery applications.