剪切流场对ABA三嵌段共聚物囊泡形貌的影响

Effect of shear field to the morphology of ABA triblock copolymer vesicles

通过同轴圆筒剪切仪和磁子搅拌方式提供的剪切流场,研究了均匀和非均匀流场对ABA两亲性三嵌段共聚物囊泡的影响.研究发现,非均匀流场下囊泡尺寸及其分散度随剪切速率的增加呈现先增大后减小的规律.与搅拌形成的非均匀流场相比,在同轴剪切仪提供的均匀流场下形成的囊泡尺寸更加均匀.结果表明,剪切流场是影响囊泡形貌的重要因素,流场的不均匀性是导致组装体形貌结构多分散性的重要原因之一.

ABA amphiphilic triblock copolymers self-assembling into vesicles were investigated in uniform shear field which generated in Couette flow cell,or in nonuniform shear field which produced by magnetic bar stirring.It was found that the size and size distribution of the vesicles first increased and then decreased as the shear rate increasing.In uniform shear flow,the size distribution of the vesicles was much narrower than that in nonuniform shear flow.The results indicated that shear flow was a key factor determines the vesicle morphology.The uniformity of the shear filed was one of the most important reasons that cause the polydispersity of the aggregate morphology.