【作者】 朱祥军；

【导师】 贺晓慧；

【作者基本信息】 南昌大学 ， 材料物理与化学， 2007， 硕士

【摘要】 本文主要采用芳香族聚酯与脂肪族聚酯固体熔融反应性共混合成可降解芳香/脂肪共聚酯。通过聚(对苯二甲酸丁二醇酯)(PBT)与D,L-低聚乳酸(OLA)在280℃反应0.5 h以上时,进行熔融酯交换合成得到了聚(对苯二甲酸丁二醇酯-co-低聚乳酸)(BLA)共聚酯。BLA共聚酯的~1H NMR谱图分析表明对苯二甲酸丁二醇酯(BT)链段与乳酸(LA)链段之间存在酯交换反应。通过BLA共聚酯链段的序列结构计算,热学性能分析,表明BLA共聚酯具有一定的无规结构。BLA共聚酯具有唯一的熔融温度(T_m),结晶温度(T_c),热分解温度(T_d)。随着OLA投入量的增加,共聚酯中芳香序列长度减少,T_m,T_c和T_d都会相应的降低。PBT/OLA进料摩尔比为5.9/94.1合成的共聚酯可溶于氯仿,而纯的PBT只能溶于氯仿/苯酚的混合溶液。凝胶渗透色谱分析(GPC)测得PBT/OLA进料摩尔比为5.9/94.1(mol/mol)的共聚酯的重均分子量为11200 g/mol。但由于BLA共聚酯力学性能较差,因此采用先将乳酸与聚乙二醇反应性共混后,再直接与PBT熔融酯交换反应合成得到了(对苯二甲酸丁二醇酯-co-聚乙二醇-co-低聚乳酸)三元共聚酯(PBTEOLA)。通过~1H NMR谱图分析证实对苯二甲酸丁二醇酯(BT)链段、聚乙二醇(EO)和乳酸(LA)链段之间存在着酯交换反应。PBTEOLA共聚酯也具有一定的无规结构。当聚(对苯二甲酸丁二醇酯)与聚乙二醇和D,L-低聚乳酸的共混物在260℃反应1.5 h时,所得PBTEOLA共聚酯具有唯一的熔融温度(T_m),结晶温度(T_c),热分解温度(T_d)。随着OLA在PEG/OLA的中的比例或者PEG/OLA的比例的增加,共聚酯的熔融温度(T_m),结晶温度(T_c)降低,同时溶解性增加。反应所得的共聚酯能溶于氯仿中,通过体积排除色谱(SEC)法测得共聚酯重均分子量能达到66600 g/mol。机械性能测试表明PBTEOLA共聚酯的杨氏模量高达50-100 MPa,断裂伸长率达32-137%。最后通过氯化钠成孔法将三元共聚酯(PBTEOLA)制备成组织工程支架后,进行细胞培养实验,发现PBTEOLA共聚酯具有较好的生物相容性。更多还原

【Abstract】 A serie of new biodegradable Aromatic-Aliphatic copolyesters materials with satisfactory thermal properties were synthesized by Melting Bulk Reactive Blending between/among Aromatic and Aliphatic polyesters. High molecular mass poly(1,4-butylene terephthalate-co-DL-lactide) (BLA) copolymers was synthesized by the Poly(1,4-butylene terephthalate) (PBT) tranesterificated with D,L-Oligo(lactic acid) (OLA) in the melt leading. The analysis from ~1H NMR reveals that transesterification is unavoidable between butylene terephthalate (BT) and lactide (LA) segments during synthesis. The BLA copolymers were confirmed to be segmented copolyesters with certain random properites as show by the sequence structure of BLA copolyester chains and by their thermal behavior. The BLA copolyesters show only one melting temperature (T_m), crystallization temperature (T_c), and thermal decomposition temperature (T_d) when the reaction between PBT and OLA takes place at 280℃for more than 0.5 h. With OLA composition increase, the T_m, T_c and T_d decrease due to fewer aromatic sequences. The copolyester with a PBT/OLA feeding molar ratio of 5.9/94.1 is soluble in chloroform, while pristine PBT is only soluble in mixed chloroform/phenol solvent. The weight-average molecular weight of the copolyester (5.9/94.1 mol/mol PBT/OLA), determined by the Gel permeation chromatography, was to be 11200 g/mol.Because of the poor mechanical property of BLA, a reactive blend of poly(ethylene glycol) (PEG) and D,L-oligo(lactic acid) (OLA) is obtained at high temperature to produce partial PEG/OLA multiblock copolymer without purification prior to preparation of copolyesters. The reactive blend of PEG/OLA multiblock copolymer easily further reacts with poly(l,4-butylene terephthalate) (PBT) in the melt leading to the formation of high molar mass poly(l,4-butylene terephthalate-co-ethylene oxide-co-D,L-lactide) (PBTEOLA) copolymers. The analysis of ~1H NMR combined with solubility test reveal that the transesterification between butylene terephthalate (BT), ethyleneoxide (EO) and lactide (LA) segments is unavoidable during synthesis. The copolyesters are segmented copolyesters with certain random properties, as confirmed by their thermal behavior. The copolyesters show only one melting temperature (T_m) on the second heating run and one crystallization temperature (T_c) on the cooling cycle from differential scanning calorimetry (DSC) measurement, and one thermal decomposition temperature (T_d) from thermogravimetry (TG) measurement when the reaction between PBT and PEG/OLA takes place at 260℃for 1.5 h. With increase of OLA feeding composition in PEG/OLA blend or increase of content of PEG/OLA blend, the T_m and T_c of copolyesters decrease, and solubility increases. The obtained copolyesters are soluble in chloroform. And the weight-averaged molecular weight of the copolyester was estimated to be as high as 66600 g/mol by the Gel permeation chromatography. Mechanical tests indicate that the copolyesters exhibit high Young’s modulus of 50-100 MPa and good elongation at break of 32-137%. A bracket of tissue engineer with poly(1,4-butylene terephthalate-co-ethylene oxide-co-DL-lactide) (PBTEOLA) copolymers was produced by using NaCl hole forming technique. Encouraging results on biocompatibility were received by initial studies of cell growth on the bracket.更多还原