Synthesis of Nano-Hydroxyapatite Surface-Grafting Poly(L-Lactide) under Microwave Irradiation
Nano-hydroxyapatite (n-HAP) surface-grafting poly(L-lactide) (g-HAP) was synthesized by ring-opening polymerization ofL-lactide (L-LA) using stannous octoate as initiator andn-HAP as co-initiator under microwave irradiation. An optimal reaction condition was obtained as follows: temperature of 140 °C, irradiation time of 45 min and microwave power of 50 W. The products were characterized by FTIR, TGA, x-ray scattering and particle size analysis. Results showed that the feeding ratio ofnn-HAP:nL-LAhad a significant influence on the grafting percentage ofg-HAP. With increasing thenn-HAP:nL-LAfeeding ratio from 1:50 to 1:400, the grafting percentage ofg-HAP increased correspondingly from 14.91% to 35.88%. Theg-HAP particles showed a smaller size than that of pristinen-HAP, suggesting that the grafted poly(L-lactide) segment facilitated to prevent theg-HAP particles from aggregating.