Synergism among Polydispersed Amphiphilic Block Copolymers Leading to Spontaneous Physical Hydrogelation upon Heating
Synergism among Polydispersed Amphiphilic Block Copolymers Leading to Spontaneous Physical Hydrogelation upon Heating
复制标题
多分散两亲嵌段共聚物之间的协同作用导致加热时自发物理水凝胶化
DOI：
10.1021/acs.macromol.0c01430
复制
发表时间：
2020-09-22
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;Chen, Liang;Ding, Jiandong
分子量分布(MWD)是合成聚合物的固有特性，影响着聚合物材料的许多性能。本工作主要通过动态蒙特卡罗模拟研究了分子量分布对两亲嵌段共聚物在水中热凝胶化的影响。摩尔质量分散度D-M被定义为重均相对分子质量M-w/数均相对分子质量M-n，它是影响溶胶-凝胶转变的存在或可胶凝时的相转变温度的关键分子参数。我们还证明了在选择性溶剂中的这种D-M效应与胶束的形成密切相关，特别是与胶束电晕的厚度有关。我们发现，多分散大分子的热凝胶化是不同长度的链之间协同作用的结果，导致了半透明胶束的渗流网络。比较分析了疏水嵌段和亲水嵌段的D-M对热凝胶化的影响。将模拟结果与已有的三嵌段共聚物PLGA-PEG-PLGA在水中的实验结果相结合，提出了D-M-M-W图用于热凝胶共聚物的设计。这一机理研究加深了对热凝胶的认识，有助于指导可注射水凝胶等生物医学领域软物质的分子工程。
Molecular weight distribution (MWD) is an intrinsic character of synthetic polymers and influences many properties of polymeric materials. In this work, the effects of MWD on thermogelation of an amphiphilic block copolymer in water were studied mainly by a dynamic Monte Carlo simulation. Molar mass dispersity D-M, defined as weight-average molecular weight M-w over number-average molecular weight M-n, was found to be a key molecular parameter to influence the existence of sol-gel transition or the phase transition temperature if gellable. We also demonstrated that such a D-M effect in a selective solvent was closely related to the formation of micelles, particularly to the thickness of micellar corona. We revealed that the thermogelation of the polydispersed macromolecules resulted from the synergism among chains of different lengths leading to a percolated network of semibald micelles. The effect of D-M of hydrophobic blocks and that of hydrophilic blocks on thermogelation were compared and analyzed. By combining the simulation results with the previous experimental results about triblock copolymer PLGA-PEG-PLGA in water [PEG: poly(ethylene glycol); PLGA: poly(lactide-co-glycolide)], we proposed a D-M-M-w diagram for design of the thermogellable copolymers. This mechanism study deepens the understanding of thermogels and is helpful for guiding the molecular engineering of such a kind of soft matter in biomedical fields as an injectable hydrogel.