动态密度泛函理论在嵌段共聚物介观结构模拟中的应用

Application of Dynamic Density Functional Theory for the Simulation of Mesoscopic Structure of Block Copolymer

采用动态密度泛函理论(DDFT)方法对两嵌段和三嵌段共聚物熔体微相分离后的三维介观结构进行了模拟研究,考察了共聚物链长N=12下组分A、B不同配比的11种两嵌段共聚物和10种三嵌段共聚物,通过等密度面图很好地表述了微相分离后的三维介观结构。通过比较序参数p、自由能F和熵S随时间的变化,发现当组分A与组分B的链节数之比NA/NB和模拟参数均相同时,两嵌段共聚物熔体比三嵌段共聚物熔体容易发生微相分离,而三嵌段共聚物越不对称,微相分离越容易。

The dynamic mean-field density functional theory (DDFT) is used to study the three-dimensional mesoscopic structure of diblock and triblock copolymer melts after microphase separation. 11 types of diblock copolymers and 10 types of triblock copolymers with the chain length N=12 are considered. The three-dimensional mesoscopic structure is obviously described by density isosurface. According to the evolutions of order parameter p、free energy F and entropy S, it is concluded that the microphase separation of diblock copolymer is easier than that of triblock copolymer at same conditions, and the more asymmetric the molecular structure is, the easier the microphase separation of triblock copolymer is.