Biodegradable thermogelling poly(ester urethane)s consisting of poly(lactic acid) - Thermodynamics of micellization and hydrolytic degradation
Biodegradable thermogelling poly(ester urethane)s consisting of poly(lactic acid) - Thermodynamics of micellization and hydrolytic degradation
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DOI：
10.1016/j.biomaterials.2008.01.016
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发表时间：
2008-05-01
期刊：
影响因子：
14
通讯作者：
Li, Jun
中科院分区：
文献类型：
--
作者：
Loh, Xian Jun;Tan, Yun Xuan;Li, Jun
合成了由聚乳酸 (PLA)、聚乙二醇 (PEG) 和聚丙二醇 (PPG) 片段组成的多嵌段聚醚酯聚氨酯，其水溶液在 7 至 9 wt% 的临界凝胶浓度 (CGC) 下表现出热凝胶行为。通过GPC、H-1 NMR、C-13 NMR和FTIR研究了共聚物的化学结构和分子特征。通过热重分析（TGA）研究聚（PEG/PPG/PLA聚氨酯）的热稳定性，并根据热降解曲线计算PLA含量。结果与 1H NMR 测量得到的结果非常吻合。使用染料溶解方法在不同温度下测定这些水溶性聚醚酯聚氨酯的临界胶束化浓度（CMC）。计算了胶束形成的热力学参数，表明该过程很大程度上是熵驱动的。有趣的是，在观察到热凝胶效应之前，系统似乎需要具有最小的熵增益。稀共聚物溶液表现出较低的临界溶解温度 (LCST) 行为，类似于溶解在水溶液中的 pNIPAM。热凝胶在 3 个月内水解降解为与组成链段相对应的聚合物片段。 (C) 2008 Elsevier Ltd. 保留所有权利。
Multiblock poly(ether ester urethane)s comprising of poly(lactic acid) (PLA), poly(ethylene glycol) (PEG), and poly(propylene glycol) (PPG) segments were synthesized, and their aqueous solutions exhibited thermogelling behavior at critical gelation concentrations (CGC) ranging from 7 to 9 wt%. The chemical structures and molecular characteristics of the copolymers were studied by GPC, H-1 NMR, C-13 NMR and FTIR. The thermal stability of the poly(PEG/PPG/PLA urethane)s was studied by thermogravimetry analysis (TGA), and the PLA contents were calculated based on the thermal degradation profile. The results were in good agreement with those obtained from the 1H NMR measurements. The critical micellization concentration (CMC) of these water-soluble poly(ether ester urethane)s was determined at different temperatures using a dye solubilization method. The thermodynamic parameters for micelle formation were calculated, indicating that the process is largely entropy-driven. Interestingly, it appears that there exists a requirement for the system to possess a minimum gain in entropy before the thermogelling effect can be observed. Dilute copolymer solutions showed a lower critical solution temperature (LCST) behavior similar to pNIPAM dissolved in aqueous solutions. The thermogels hydrolytically degraded to polymer fragments corresponding to the constituent segment blocks within 3 months. (C) 2008 Elsevier Ltd. All rights reserved.