循环溶剂退火条件下柱状相组成的两嵌段共聚物薄膜自组装行为的模拟研究  

Self-assembly of Diblock Copolymer Films upon Cyclic Solvent Annealing:A Simulation Study

作　　者：胡卨俊 郝金龙 王铮 尹玉华 蒋润 李宝会 Xie-jun Hu;Jin-long Hao;ZhengWang;Yu-hua Yin;Run Jiang;Bao-hui Li(Key Laboratory of Functional Polymer Materials of Ministry of Education,School of Physics,Nankai University,Tianjin 300071)

机构地区：[1]南开大学物理科学学院,教育部功能高分子材料重点实验室,天津300071

出　　处：《高分子学报》2021年第10期1379-1389,共11页Acta Polymerica Sinica

基　　金：国家自然科学基金(基金号21574071,21774066,21528401,21829301);教育部创新团队发展计划(项目号IRT1257);高等学校学科创新引智111计划(项目号B16027)项目;外国文化教育专家项目(项目号G20190002001)资助。

摘　　要：采用蒙特卡洛模拟研究了体相形成柱状相的两嵌段共聚物薄膜在循环溶剂退火条件下的自组装行为.结果表明,在循环溶剂退火条件下,溶剂蒸发速率、溶剂选择性和有效薄膜厚度与柱状相周期的匹配性都会影响形成垂直柱状结构的表面选择性窗口(β窗口).当溶剂蒸发速率在一定范围内时,β窗口随蒸发速率的增大而增大.溶剂对长嵌段的选择性越强,形成垂直柱状结构的β窗口越宽.当溶胀比约为1.5时的薄膜厚度与柱状相周期不匹配时更利于形成垂直柱状结构.通过对链节均方位移曲线的分析发现,在循环溶剂退火条件下高分子链节在垂直方向的扩散始终快于平行方向,因此链节优先沿垂直方向聚集,从而促进了垂直柱状结构的形成.循环溶剂退火条件下,β窗口比溶剂退火条件下的宽,同时大幅度减少了退火时间.Solvent(-vapor)annealing(SA)has been widely used to promote the formation of perpendicularly oriented structures in self-assembly of block copolymer thin films.In SA,as-prepared block copolymer films are exposed to the vapor of solvent to form a swollen and mobile polymer film atop the substrate,and finally the solvent is evaporated.Tranditional SA contains only one swollen-evaporation process,while cyclic solvent annealing(CSA)contains multiple swollen-evaporation processes in a cyclic means.The existence of solvent affects the effective interaction between the blocks,the effective film thickness,the effective surface preference,and the effective volume fractions of the blocks,and hence affects the resulting morphology.The morphologies induced by the presence of solvent may be trapped during the solvent evaporation process.Hence,the resulting morphology after SA/CSA may be quite different from that without SA/CSA treatment.Furthermore,the swollen evaporation processes in CSA can be designed to facilitate the formation of perpendicularly-orientated structures.In this study,we present our lattice Monte Carlo simulation results of the self-assembly for cylinder-forming diblock copolymer films under CSA.Our simulations are based on the“single-site bond fluctuation”model,and it is assumed that the maximum swelling ratio of the film in each swollen-evaporation cycle decreases linearly with the increase of the cycle number.This assumption ensures that relatively large rearrangement of microdomains occurs when the number of cycles is relatively small,and the resulting characteristic structure can be kept effectively in the following cycles.The results show that the surface preference window(β-window)of perpendicular cylinders is affected by the solvent evaporation rate,solvent selectivity and commensurability between the film thickness and the bulk period.When the solvent evaporation rate is intermediate,theβ-window enlarges with increasing it.A stronger solvent selectivity for the majority block as well as dismat

关 键 词：嵌段共聚物 循环溶剂退火 取向 柱状相 

分 类 号：TQ317[化学工程—高聚物工业] TB383.2[一般工业技术—材料科学与工程]