Abstract:

Poly(glycolic acid) (PGA) is usually prepared by ring-opening polymerization of glycolide and melt polycondensation of glycolic acid. However, the ring-opening polymerization process of glycolide is complicated, resulting in the high cost of PGA. In contrast, the preparation of PGA by melt polycondensation of glycolic acid has simple process and low cost, but it is difficult to obtain the medium- and high-molecular-weight PGA. In this work, the effects of polymerization process conditions such as catalyst type and content, esterification temperature and solid-state polycondensation temperature on the appearance, intrinsic viscosity and thermal stability of PGA were systematically studied in the melt/solid-state polycondensation route. It is found that bismuth trifluoromethanesulfonate had good catalytic effect on the melt polycondensation of glycolic acid. The optimal melt/solid-state polycondensation conditions were as follows: the catalyst content of 0.20%(mass), the esterification temperature of 180℃, the melt polycondensation and solid-state polycondensation temperatures of 210℃, and the solid-state polycondensation time of 12 h. Under such optimal melt polycondensation conditions, the highest intrinsic viscosity of PGA was 0.36 dl/g. The intrinsic viscosity of PGA can be increased to 0.59 dl/g by further solid-state polycondensation.

Key words: glycolic acid, melt/solid-state polycondensation, poly(glycolic acid), polymerization process

摘要：

聚乙醇酸（PGA）通常可通过乙交酯开环聚合和乙醇酸熔融缩聚制得，但乙交酯开环聚合工艺复杂，导致PGA成本高。相较而言，乙醇酸熔融缩聚制备PGA工艺简单，成本较低，但难以获得中高分子量的PGA。因此，本文基于熔融/固相缩聚路线，系统研究了催化剂种类与含量、酯化温度、固相缩聚温度等聚合工艺条件对PGA外观形态、特性黏度和热稳定性的影响。发现三氟甲烷磺酸铋对乙醇酸熔融缩聚具有较好的催化效果，优化熔融/固相缩聚条件如下：催化剂含量为0.20%（质量），酯化温度为180℃，熔融缩聚和固相缩聚温度为210℃，固相缩聚时间为12 h。在该熔融缩聚条件下，PGA的最高特性黏度为0.36 dl/g，进一步固相缩聚处理可以将PGA的特性黏度提高到0.59 dl/g。

关键词: 乙醇酸, 熔融/固相缩聚, 聚乙醇酸, 聚合工艺