Synthesis of poly(D-lactide) with different molecular weight via melt-polymerization

Polylactide is considered as Green Polymer due to its sustainability. Poly(D-lactide) is absolutely required in order to make stereocomplex polylactide. But, there is no report about D-lactide polymerization. Various molecular weight of poly(D-lactide) were successfully polymerized from D-lactide in the melt stage using various catalysts. Stannous octoate, aluminum isopropoxide and lanthanum isopropoxide has better solubility in the molten monomer compared to yttrium isopropoxide oxide. We obtained high conversion (99.17%) and high molecular weight (M (n) =384,992) using stannous octoate. We also obtained high conversion (94.46%) and medium molecular weight (M (n) =78,634) using aluminum isopropoxide. This data is suitable for industrial applications. In the kinetic study, stannous octoate has higher polymerization rate (k (p) =10.8x10(-2) min(-1)) compared to the aluminum isopropoxide (k (p) =7.3x10(-2) min(-1)).