Study on the synthesis of poly (D, L-lactide)

Poly (D, L-lactide) (PDLLA) was synthesized by ring-opening polymerization of D, L-lactide. The effects of the synthesis conditions such as monomer (lactide) purity, catalyst (stannous octoate) concentration, vacuum level, reaction time and temperature, were discussed. The PDLLA with a viscosity average molecular weight (Mη) beyond 20 × 10⁴ was obtained under the optimum synthesis conditions of the lactide after being recrystallized 4 times as the monomer, the vacuum level of 0.098 MPa, reaction temperature of 150-160 °C, reaction time of 6-8 h, and using 0.1%-0.18% stannous octoate as catalyst. The structure of polymer was characterized by FTIR and ¹H-NMR.