The Study on Crystallization Behavior of Bacterially Synthesized Copolyesters by High-Resolution Solid-State NMR

本研究采用高分辨固体碳谱、差示扫描量热法和偏光显微镜研究了几种细菌共聚酯的结晶行为与组成的关系，考察了细菌聚(3-羟基丁酸酯-4-羟基丁酸酯)(P3HB-4HB)在较大范围内的结晶状态。分析了化学合成的聚对苯二甲酸乙二醇酯-1，4-环己二亚甲基对苯二甲酸乙二醇酯(PET-CHT)的结晶同象。结果表明，对于CHT含量较高的共聚物，两个单体单元在一定程度上实现了共结晶；细菌聚(3-羟基丁酸酯-3-羟基戊酸酯)的组成分布非常广泛，对结晶行为有显著影响；还研究了3HP含量为0~37mol%的细菌聚(3-羟基丁酸酯-3-羟基丙酸酯)(P3HB-3HP)的固相结构。结果表明，P3HB-3HP的结晶区仅由3HB单元组成，说明P3HB-3HP中不存在共结晶现象。

In this study, composition dependence of crystallization behavior of some bacterial copolyesters has been studied by high-resolution solid state C-13 NMR,DSC,and polarized microscopy.The crystalline states of bacterial poly (3-hydroxybutyrate-co-4-hydroxybutyrate) (P3HB-4HB) with a wide range of 4HB contents were investigated. It was demostrated that P3HB-4HB can not form isomorphic crystals because of the extent of the structural difference between the 3HB and 4HB units.Crystal isomorphism of chemically synthesized poly (ethylene terephthalate-co-1,4-cyclohexenedimethylene terephthalate) (PET-CHT) was analyzed. It was found that cocrystallization of the both monomer units is realized to some extent for the copolymers with high CHT unit content.The composion distribution of bacterial poly (3-hydroxybutyrate-co-3-hydroxyvalerate) was found to be extremely broad and it attects significantly the crystallization behavior.The solid state structure of bacterial poly (3-hydroxybutyrate-co-3-hydroxypropionate) (P3HB-3HP) with 3HP content ranged from 0 to 37mol% was also studied. It was found that the crystalline region was composed of only the 3HB unit, suggesting that the cocrystallization does not occur in P3HB-3HP.