分子量多分散性对AB二嵌段共聚物相行为的影响

采用Monte Carlo方法研究了分子量多分散性对AB型嵌段共聚物相行为的影响. 通过调整嵌段共聚物中组分含量, 考察了整体多分散性和单嵌段多分散性对嵌段共聚物共混物的有序-无序转变(Order-disorder transition, ODT)、 形貌及链尺寸的影响. 研究结果表明, 多分散度的增大使无序相向较大χN区域略微移动, 形成的片层结构厚度增加. 在形成微观有序形貌后, 较大分散度时各亚组分的链会得到更大的伸展, 表明分子链堆积受挫的程度减小, 因此, 涨落作用受到的抑制作用减小, 无序相区向更低温度区域移动.

Polydispersity Effect on Phase Behavior of Diblock Copolymer

Effect of polydispersity on phase behavior of diblock copolymer was studied by Monte Carlo simulation.In order to evaluate the polydispersity effect,block copolymer blends including three different components were utilized as models in the simulation.By controlling the weight fractions of the component in copolymer blend,the influence of two different types of polydispersity effects(i.e.overall polydispersity effect and single block polydispersity effect,respectively) on order-disorder transition(ODT),conformations,and chain size of polymers were investigated.The results show that the increasing of index of polydispersity(PDI) can cause the ODT temperature slightly shifts to a lower temperature region.And it can also induce the increasing of the spacing thickness of the newly formed lamellar structure.Based on microscopic conformation analysis,polymer chains tend to stretch more at larger PDIs,which reveals the decreasing of accumulation degree of polymer chains.Therefore,the inhibition effect on fluctuation diminishes and the disordered phase shifts to the lower temperature region.