Synthesis and Structure Control of L-Lactic Acid-Glycolic Acid Copolymer by Homo-Copolymerization

摘要

A two-step direct melt copolymerization process of l-lactic acid (L-LA)/glycolic acid (GA) was developed: poly(l-lactic acid) (PLLA) and poly(glycolic acid) (PGA) with different molecular weight was first synthesized respectively by binary catalyst (tin chloride/p-toluenesulfonic or tin chloride); and then poly(l-lactic-co-glycolic acid) (b-PLGA) was produced by melt polymerization of the as-prepared PLLA and PGA, wherein the composition and chain structure of b-PLGA copolymers could be controlled by the molecular weight of PLLA. The chain structure and thermal properties of copolymers were studied by Wide-angle X-ray diffraction, nuclear magnetic resonance, differential scanning calorimetry, and thermogravimetric analysis. In comparison with the random PLGA (r-PLGA) synthesized by one-step direct melt polymerization, the average l-lactic blocks length (L-LA) in b-PLGA was longer while the average glycolic blocks length (L-GA) in b-PLGA was shorter which further resulted in the improved crystallinity and thermostability. (c) 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41566.