作者：Xuan Feng, Nan Yan, Jing Jin, Wei Jiang
关键字：分子动力学模拟, 两亲性AB嵌段共聚物, 囊泡解组装, 选择性溶剂, 环形胶束
论文来源：期刊
具体来源：Macromolecules, 2023, 56(6), 2560-2567
发表时间：2023年

摘要：本文通过分子动力学模拟研究了两亲性AB嵌段共聚物在选择性溶剂中的解组装行为。从一个初始组装体解组装为不同聚集体由依赖体系不稳定性的热力学过程控制。基于该策略，A2BxB18-x两嵌段共聚物中的Bx可在光、pH等外部刺激下转变为Ax，稳定态A2BxB18-x共聚物囊泡在A2BxB18-x共聚物转变为A2AxB18-x后变得不稳定。模拟结果表明，Bx转变引起的体系不稳定性是x的函数，x越大，不稳定性越高；通过增大x，组装体可从初始囊泡解组装为环、棒、球、无序聚集体以及完全分散的聚合物链。值得注意的是，其中一些结构无法由初始均相态自组装获得。以x=5为例，将A2B5B13转变为A7B13可获得环形胶束，而相同条件下A7B13嵌段共聚物无法从均相态自组装得到。此外，除x值外，Bx转变速率和聚合物链转变数量也会影响解组装，环形胶束在慢Bx转变速率下无法形成。

Abstract：The disassembly of amphiphilic AB block copolymers in selective solvents by molecular dynamic simulation is investigated in this study. The disassembly from one initial assembly into different aggregates is controlled by thermodynamic processes that depend on the instability of the system. Based on this strategy, Bx can be converted to Ax in A2BxB18-x diblock copolymers (where x is a variable integer) by external stimuli such as light and pH. The A2BxB18-x copolymer vesicle in a stable state becomes unstable when A2BxB18-x copolymers are converted to A2AxB18-x copolymers. The simulation results show that the instability of the system induced by Bx conversion is a function of x, and the larger x, the higher the instability. The assembly can thereby disassemble from the initial vesicle into a ring, rod, sphere, disorder aggregate, as well as completely dispersed polymer chains by increasing x. Notably, some of those structures cannot be obtained by self-assembly from the initial homogeneous state. Taking x=5 as an example, toroid micelles are obtained by converting A2B5B13 into A7B13, whereas they are not obtained by self-assembly from a homogeneous state for the A7B13 block copolymer under the same conditions. Moreover, in addition to the x value, the Bx conversion rate and the converted amount of polymer chains can also affect the disassembly. Toroid micelles are impossible to form under a slow Bx conversion rate.

论文链接：https://doi.org/10.1021/acs.macromol.2c02352