Molecular and material design of aliphatic polyesters with controlled biodegragradability

到目前为止，各种脂肪族聚酯已被合成为可生物降解的聚合物。众所周知，它们的生物降解性在很大程度上取决于结晶度以及晶体的大小和形态。本研究通过新单体的开环聚合和可控的直接缩聚，设计合成了多种具有生命可控降解性的可生物降解聚酯，如在聚(3-羟基丁酸)(PHB)中引入乙醇酸和苹果酸单元，以增强PHB的水解性，为PHB的功能化提供广泛的选择。将12-羟基硬脂酸(12HSA UNTI)通过开环共聚的方法引入到聚L-乳酸(PLLA)中，得到了一种柔软的PLLA衍生物。还研究了L-乳酸与扁桃酸的共聚反应，得到了玻璃化转变温度较高、降解性较好的玻璃化生物可降解共聚物。…通过聚乳酸与L-丙交酯的开环共聚反应，制备了聚乳酸与聚氧乙烯嵌段共聚物，并将其分散在水中，制得了核壳纳米粒子。从这些粒子中，螺旋PLLA嵌段的结晶形成了特定的带状结构。发现A-B-A三嵌段共聚物PLLA-PEGPLLA和PDLA-PEGPDLA在分散相混合时发生了Sol-Gel转变。这种转变是由PLLA和PDLA链的立体络合作用驱动的。采用熔融纺丝法制备了以聚乙醇酸(PGA)和聚乳酸(PLLA)为芯层和皮层的芯鞘双组分纤维。利用洋葱假单胞菌来源的脂肪酶对聚琥珀酸丁二醇酯(PBS)及其衍生物聚对苯二甲酸丁二醇酯(PBST)进行了酶促降解研究。PBS和PBST分别通过酯键的外向和内向断裂进行生物降解。较少

Various aliphatic polyesters have been synthyesized as biodegradable polymers thus far. Their biodegradability has been known to depend largely on the crystallinity as well as on the crystal size and morphology. In this research, various biodegradable polyesters having life-controlled degradability are designed and synthesized by ring-opening polymerization of new monomers and by well-controlled direct polycondensation.For example, glycolate and malate units were introduced into poly (3-hydroxybutyric acid) (PHB) to enhace the hydrolyzability of PHB and to have wide options for the functionalization of PHB. 12-Hydroxystearic acid (12HSA unti was also incorporated into poly (L-lactic acid) (PLLA) by ring-opening copolymerization of L-lactide and cyclic dimer of 12HSA in order to attain a soft PLLA derivative. Copolymerization of L-lactic acid with mandelic acid was also conducted to obtain glassy biodegradable copolymer with high glass transition temperature and increase degradability. … More Block copolymers of PLLA and poly (oxyethylene) (PEG) were prepared by the ring-opening copolymerization of PEG and L-lactide and dispersed into water to obtain core-shell nanoparticles. From these particles, a specific band structure was formed by the crystallization of the helical PLLA blocks. Sol-gel transition was found to occur on mixing the disperisions of the enationmeric A-B-A triblock copolymers, PLLA-PEG-PLLA and PDLA-PEG-PDLA. This transition was driven by the stereo-complexation of the PLLA and PDLA chains. The core-sheath bicomponent fiber consisting of poly (glycolic acid) (PGA) and PLLA as the core and sheath, respectively, was processed by melt-spinning. The fiber showed higher degradability than the single PLLA fiber.Enzymatic degradation of poly (butylene succinate) (PBS) and its derivative, poly (butylene succinate-co-terephthalate) (PBST) was studied by using a lipase originated from Pseudomonas cepacia. PBS and PBST was biodegraded by exo-type and endo-type scission of ester linkage, respectively. Less