作者：Juanjuan Fan, Jie Cui, Yuanyuan Han, Wei Jiang
关键字：Monte Carlo模拟, 温度响应, 可逆形貌转变, AB两嵌段共聚物, 球形胶束, 囊泡
论文来源：期刊
具体来源：RSC Advances, 2014, 4(92), 50351-50360
发表时间：2014年

摘要：采用Monte Carlo模拟研究了AB两嵌段共聚物在A嵌段选择性溶剂中由温度诱导的球形胶束与囊泡之间可逆形貌转变。当仅疏水B嵌段对温度敏感时，随着温度降低，胶束由高温下的球形转变为囊泡；将体系重新加热到高温后，囊泡又转变为球形，表现出随温度变化的可逆形貌转变。然而，形貌转变路径依赖于温度变化速率：淬火过程中球形变为囊泡的路径，与直接加热时囊泡变为球形的路径不同，且加热时囊泡转变为球形所需模拟时间显著短于淬火时反向过程。而逐步改变温度时，两种转变路径几乎相同，退火与逐步升温所需时间也接近。通过追踪B嵌段与溶剂接触数随模拟时间的变化，进一步阐明了直接与逐步改变温度时路径差异的机制。当亲水和疏水嵌段均具温度敏感性时，退火条件下亲水嵌段的温度敏感性会阻碍球形向囊泡的转变，若A嵌段温度敏感程度较高，退火后只能得到较大球形胶束；但在缓慢变温速率下，形貌转变仍可逆。

Abstract：Temperature-induced reversible morphological changes of micelles formed by AB diblock copolymers in a selective solvent for A blocks were studied through Monte Carlo simulation. When only hydrophobic B blocks are temperature-sensitive, the micelle morphology changes from sphere at high temperature to vesicle with a decrease in temperature, and the vesicles transform back into spheres upon heating, indicating reversible morphological changes with temperature. The pathways of morphological changes depend on the temperature change rate: the sphere-to-vesicle pathway under a quenching process differs from the vesicle-to-sphere pathway upon direct heating, and the time for vesicle-to-sphere transformation upon heating is significantly shorter than that for the reverse process upon quenching. When the temperature is changed gradually, the pathways are almost identical and the simulation times are nearly the same. When both hydrophilic and hydrophobic blocks are temperature-sensitive, the temperature-sensitivity of hydrophilic blocks hinders the sphere-to-vesicle transition under annealing conditions, and only larger spheres can be obtained after annealing when the degree of temperature-sensitivity of block A is rather high. The morphological transitions are still reversible under a slow temperature change rate.

论文链接：https://doi.org/10.1039/c4ra04112g