酶催化一步法制备高分子质量PBSA共聚酯及其性能

聚丁二酸丁二醇酯(PBS)是一种具有广阔发展前景的生物基聚酯品种,但由于其分子链段柔性较高并且结晶度高,在实际应用过程中仍然面临热性能、力学性能、降解性能不足的弊端。选用条件更为温和的酶催化体系,以丁二酸二乙酯、己二酸二乙酯、丁二醇为原料,Novozym-435(固定化CALB酶)为催化剂,甲苯为溶剂,合成制备了一系列高分子质量的聚(丁二酸丁二醇-co-己二酸丁二醇)(PBSA)三元共聚酯。在反应温度80℃、酶的质量分数为10%的条件下,所制备的PBS与PBSA共聚酯的数均分子质量在18 400~21 200 g/mol,多分散性指数在1.7~2.0之间。采用核磁共振谱仪对制备的共聚酯产物的化学结构进行了表征。TGA结果表明,酶催化体系下的PBSA共聚酯的热稳定性要高于熔融体系下的产物。DSC与WAXD的结果表明,引入己二酸链段后,PBS的结晶能力下降。酶催化反应避免了重金属催化剂的使用,进一步拓宽了PBS在生物医药领域范围的潜在应用。

Lipase-Catalyzed Synthesis of High Molecular PBSA Copolyester and the Study on Its Properties

As an essential biodegradable polyester,poly(butylene succinate)is a highly promising species.However,due to the high flexibility of its segments and high crystallinity,poly(butylene succinate)is still restricted for wider applications because of its low thermal and mechanical properties and unsatisfactory biodegradability.A series of high molecular weight poly(butylene succinate-co-butylene adipate)(PBSA)co?polyesters constructed with diethyl succinate,diethyl adipate,1,4-butanediol are synthesized by using a moderate enzyme catalyst Novozym-435(immobilized Candida antarctica lipase B)through the azerotrope method.Under the reaction temperature 80℃and the enzyme concentration 10%,the Mn value of prepared PBS and PBSA is in the range of 18400~21200 g/mol,and its corresponding molecular weight distribution is in the range of 1.7~2.0.TGA results show that the thermal stability of the samples from enzyme catalyzed polymerization is higher than that of the products from the melten polymerization.DSC and WAXD results show that the crystallization ability of PBS reduced after adipate acid is introduced.Additionally,since the use of metal catalysts is avoided in the reaction,the potential application of PBS in the biomedical field is further widened.