Thermogelling of Amphiphilic Block Copolymers in Water: ABA Type versus AB or BAB Type
Thermogelling of Amphiphilic Block Copolymers in Water: ABA Type versus AB or BAB Type
复制标题
两亲性嵌段共聚物在水中的热凝胶化：ABA 型与 AB 或 BAB 型
DOI：
10.1021/acs.macromol.9b00534
复制
发表时间：
2019-05-28
期刊：
影响因子：
5.5
通讯作者：
Ding, Jiandong
中科院分区：
文献类型：
--
作者：
Cui, Shuquan;Yu, Lin;Ding, Jiandong
一些两亲性嵌段共聚物在水中加热时表现出溶胶-凝胶转变，这为临床上提供了一种有前途的可注射热凝胶和一种有趣的软物质体系。虽然阿坝-，BAB-和AB-型嵌段共聚物都已报道，很少有人知道这些聚合物类型的超分子结构的比较研究的物理水凝胶，这阻碍了理解的普遍机制，在热凝胶化过程中的结构变化。本文通过实验和计算机模拟研究了阿坝三嵌段共聚物聚（D，L-丙交酯-共-乙交酯）-b-聚（乙二醇）-b-聚（D，L-丙交酯-共-乙交酯）的热凝胶水体系，并以相应的AB二嵌段共聚物和BAB三嵌段共聚物作为对照。采用开环聚合法合成了共聚物，并利用透射电镜、三维动态光散射等方法研究了共聚物在水中的热凝胶行为。荧光共振能量转移，温度依赖的C-13 NMR，和流变学测量也进行了调查的内部结构和它们的演变过程中的溶胶-凝胶转变。采用动态Monte Carlo模拟进一步分析了热凝胶化过程。在阿坝嵌段共聚物的热凝胶窗口中发现了两种不同结构的状态。从semibald胶束演变的疏水通道的形成被揭示为触发所有类型的热凝胶化共聚物的物理凝胶化的关键通用线索。基于我们的结构研究，热凝胶共聚物的分子设计原则已经建立。
Some amphiphilic block copolymers exhibit sol gel transition in water upon heating, which affords a promising injectable thermogel in clinic and an interesting soft matter system. While ABA-, BAB-, and AB-type block copolymers have all been reported, little is known about the comparative study of supermolecular structures of these polymer types in the physical hydrogels, which hinders the understanding of the universal mechanism of structural changes during thermogelling. Herein, a thermogellable aqueous system of ABA triblock copolymer poly(D,L-lactide-co-glycolide)-b-poly(ethylene glycol)-b-poly(D,L-lactide-co-glycolide) was investigated by both experiments and computer simulations, with the corresponding AB diblock copolymer and BAB triblock copolymer as controls. The copolymers were synthesized via ring-opening polymerization, and their thermogelling behaviors in water were analyzed with transmission electron microscopy, three-dimensional dynamic light scattering, and so forth. Fluorescence resonance energy transfer, temperature-dependent C-13 NMR, and rheological measurements were also carried out to investigate the internal structures and their evolutions during the sol gel transition. A dynamic Monte Carlo simulation was operated to analyze the thermogelation further. We found two states with different structures in the thermogel window of the ABA block copolymer. The formation of a hydrophobic channel evolved from the semibald micelle was revealed as the key universal cue triggering the physical gelation for all types of thermogellable copolymers. Based on our structural studies, the molecular design principles for the thermogellable copolymers have been established.