Direct synthesis of biodegradable ploy L-lactic acid by melt polycondensation
- VernacularTitle:生物降解材料聚L-乳酸的熔融缩聚合成
- Author:
Jing SHU
;
Peng WANG
;
Tong ZHENG
;
Liuyi TIAN
;
Baoxiu ZHAO
- Publication Type:Journal Article
- From:
Chinese Journal of Tissue Engineering Research
2008;12(6):1165-1169
- CountryChina
- Language:Chinese
-
Abstract:
AIM: To synthesize biodegradable poly lactic acid (PLA) through the optimization and selection of process and catalyst.METHODS: This experiment was performed at the Research Center for Green Chemistry and Technology in the School of Municipal and Environmental Engineering of Harbin Institute of Technology from February 2003 to October 2004. Biodegradable poly L-lactic acid (PLLA) was synthesis by melt polycondensation using L-lactic acid (LA) as material. Firstly, oligo L-lactic acid (OLLA) was prepared by dehydrating aqueous solution of LA without catalyst. And then, the mixture of OLLA and catalyst was heated at a certain temperature and pressure for a period of time to get the product of PLLA. The structure of PLLA was characterized by Fourier transform infrared (FTIR) spectra and 1H- nuclear magnetic resonance (1H-NMR) spectra. The polydispersity was determined by gel permeation chromatography (GPC).RESULTS: OLLA with the viscosity average molecular weight (Mη) of 6 500 g/mol was prepared by the following steps: the solution of LA without catalyst was dehydrated at 140 ℃, first at reduced pressure of 30 kPa for 2 hours, and then at 5 kPa for 4 hours. SnCl2-p-toluenesulfonic acid (TSA) system was the effective catalyst for the polycondensation of OLLA. After the mixture of OLLA and catalysts polycondensed at 165 ℃ and 5 kPA for about 8 hours, PLLA with the Mη of 65 000 g/mol was obtained by using SnCl2-TSA system as catalyst with the SnCl2 amount of 0.4wt% to OLLA and equal mol ratio of SnCl2 and TSA.CONCLUSION:PLLA with a certain practicability was obtained under the optimal process and catalyst. Oligomerization of LA played an important role on improving the molecular weight of PLLA.
