Thermal properties of Copoly (L-lactic acid/ glycolic acid) by Direct Melt Polycondensation

摘要

A two steps direct copolymerisation process of L-lactic acid(L-LA)/glycilic acid(GA) was developed. The first step is to produce oligomer of L-LA/GA and then the oligomer was polymerized with binary catalyst tin chloride dihydrate/p-toluenesulfonic acid. In this way, the copoly(L-LA/GA) (PLGA) without any organic solvent was synthesized directly. The thermal properties of PLGA were studied by differential scanning calorimetry (DSC) and nuclear magnetic resonance (NMR). The results show that the melting point of PLGA decreases with increasing the mole fraction of GA units in copolymer. In addition, the melting point of polymer also decreases with increasing the degree of racemization of polymer.