Polystyrene-b-poly(2,2,2-trifluoroethyl acrylate)s (PS-b-PTFEAs) are a high-χ block copolymer (BCP) system possessing high potential for fabricating sub-10 nm nanoscopic patterns, however, their thin film implications are limited by the substantially large surface energy difference between the two blocks. Herein, we investigate how to direct the lamellae perpendicular to the substrates and uniaxial along the electric vector via a thermal annealing process. For PS-b-PTFEA films supported on a neutral-like underlying homopolymer mat, we modulate the interfacial interactions of top-coat random copolymers by controlling the molar ratios of S to TFEA units with polarity-switchable maleic anhydride. Intriguingly, the neutral top-coat interactions for PS-b-PTFEA films occur at a highly asymmetric composition with a larger S fraction to suppress lower surface energy of the PTFEA block. Under such a neutral confinement on both the top surface and bottom simultaneously, the BCP films subjected to a lateral electric field exhibit a directed orientation of perpendicular lamellae along the electric vector. Notably, a short period (5 min) of treatment is enough for the PS-b-PTFEA film to produce uniaxial alignment of sub-10 nm-scale perpendicular lamellae under a direct current potential of 25 V/μm. This fast directed assembly kinetics is likely because of rapid chain diffusion of short segments in synergy with high dielectric contrast between the two components.

中文翻译：

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氟丙烯酸嵌段共聚物薄膜和快速电场定向组装的平衡界面相互作用

聚苯乙烯-b-聚（2,2,2-三氟乙基丙烯酸酯）（PS- b - PTFEAs）是一种高χ嵌段共聚物（BCP）系统，具有制造10纳米以下纳米图案的潜力，但它们的厚度薄薄膜的含义受到两个块之间相当大的表面能差的限制。在本文中，我们研究如何通过热退火工艺将薄片垂直于基板定向并沿电矢量单轴定向。对于负载在中性状基础均聚物垫上的PS- b - PTFEA薄膜，我们通过控制S与TFEA单元的摩尔比和极性可切换的马来酸酐来调节面涂无规共聚物的界面相互作用。有趣的是，PS-b -PTFEA膜以高度不对称的成分出现，且S分数较大，从而抑制了PTFEA嵌段的较低表面能。在顶面和底面同时进行这种中性约束的情况下，受到侧向电场作用的BCP薄膜沿电矢量表现出垂直薄片的定向取向。值得注意的是，短时间的处理（5分钟）足以使PS- b - PTFEA膜在25 V /μm的直流电势下产生低于10 nm尺寸的垂直薄片的单轴排列。这种快速定向的组装动力学很可能是由于短链段的快速链扩散与两个组分之间的高介电对比度协同作用。