Immobilized Candida antarctica lipase B (CALB)-catalyzed polycondensation of glycerol and sebacic acid at mild reaction conditions resulted in branched poly(glycerol sebacate) (PGS). To understand how PGS chains grow and branch, the kinetics of the CALB-catalyzed polycondensation were studied. The influence of the reaction temperature, solvent, CALB amount, and sebacic acid/glycerol feed ratio on the poly(glycerol sebacate) (PGS) molecular weight, degree of branching, and glyceridic repetitive unit distribution was also investigated. PGS architecture changes from linear to branched with the progression of the reaction, and the branching results from the simultaneous CALB-catalyzed esterification and acyl migration. For reactions performed in acetone at the temperature range from 30 to 50 °C, the apparent rate constant increases from 0.7 to 1.5 h^–1, and the apparent energy of activation of 32 kJ mol^–1 was estimated. The higher mass average molecular weight (16 kDa) and degree of branching (41%) were achieved using the equimolar sebacic acid/glycerol feed ratio in acetone at 40 °C with a CALB amount of 13.6 wt % and in the presence of the molecular sieves.

中文翻译：

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聚癸二酸甘油酯的酶促合成：动力学，链增长和支化行为

固定化南极假丝酵母脂肪酶B（CALB）催化的甘油和癸二酸在温和的反应条件下的缩聚反应生成支化的聚癸二酸甘油酯（PGS）。为了了解PGS链如何生长和分支，研究了CALB催化的缩聚反应的动力学。还研究了反应温度，溶剂，CALB量和癸二酸/甘油进料比对聚癸二酸甘油酯（PGS）分子量，支化度和甘油重复单元分布的影响。PGS体系结构随反应的进行从线性变为支化，而支化是由同时发生的CALB催化的酯化和酰基迁移所致。对于在30至50°C的温度范围内在丙酮中进行的反应，表观速率常数从0.7增加至1.5 h ^–1，估计活化的表观能量为32 kJ mol ^–1。在40°C下使用等摩尔的癸二酸/甘油进料比率在40°C下以CALB的13.6 wt％的当量摩尔比在癸二酸/甘油进料中获得了更高的质均分子量（16 kDa）和支化度（41％）筛子。