Locally Favored Two-Dimensional Structures of Block Copolymer Melts on Nonneutral Surfaces,Macromolecules

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Locally Favored Two-Dimensional Structures of Block Copolymer Melts on Nonneutral Surfaces
Macromolecules ( IF 5.1 ) Pub Date : 2018-01-10 00:00:00 , DOI: 10.1021/acs.macromol.7b02506
Mani Sen ₁ , Naisheng Jiang ₁ , Maya K. Endoh ₁ , Tadanori Koga _{1,

2} , Alexander Ribbe ₃ , Atikur Rahman ₄ , Daisuke Kawaguchi , Keiji Tanaka , Detlef-M. Smilgies ₅

Affiliation

Self-assembly of block copolymers (BCPs) into arrays of well-defined nanoscopic structures has attracted extensive academic and industrial interests over the past several decades. In contrast to the bulk where phase behavior is controlled by the segmental interaction parameter, the total number of segments in BCPs and volume fraction, the morphologies and orientations of BCP thin films can also be strongly influenced by the substrate surface energy/chemistry effect (considered as a “substrate field”). Here, we report the formation of locally favored structures where all constituent blocks coexist side-by-side on nonneutral solid surfaces irrespective of their chain architectures, microdomain structures, and interfacial energetics. The experimental results using a suite of surface-sensitive techniques intriguingly demonstrate that individual preferred blocks and nonpreferred blocks lie flat on the substrate surface and form a two-dimensional percolating network structure as a whole. The large numbers of solid-segment contacts, which overcome a loss in the conformational entropy of the polymer chains, prevent the structure relaxing to its equilibrium state (i.e., forming microdomain structures) even in a (good) solvent atmosphere. Our results provide direct experimental evidence of the long-lived, nonequilibrium structures of BCPs and may point to a new perspective on the self-assembly of BCP melts in contact with impenetrable solids.

中文翻译：

非中性表面嵌段共聚物熔体的局部二维结构

在过去的几十年中，将嵌段共聚物（BCP）自组装成定义明确的纳米结构的阵列吸引了广泛的学术和工业兴趣。与通过段相互作用参数控制相行为的本体相比，BCP中段的总数和体积分数，BCP薄膜的形态和取向也可能受到基材表面能/化学效应的强烈影响（考虑到作为“底物领域”）。在这里，我们报告了局部偏爱的结构的形成，其中所有组成块在非中性固体表面上并排共存，无论它们的链结构，微区结构和界面能量学如何。使用一组表面敏感技术的实验结果有趣地证明，各个优选的嵌段和非优选的嵌段平整地位于基底表面上，并且整体上形成了二维渗滤网络结构。克服了聚合物链构象熵损失的大量固相接触，即使在（良好）溶剂气氛中，也可以防止结构松弛到其平衡状态（即，形成微区结构）。我们的结果提供了BCP的长寿命非平衡结构的直接实验证据，并且可能为BCP熔体与不可渗透的固体接触的自组装提供了新的视角。克服了聚合物链构象熵损失的大量固相接触，即使在（良好）溶剂气氛中，也可以防止结构松弛到其平衡状态（即，形成微区结构）。我们的结果提供了BCP的长寿命非平衡结构的直接实验证据，并且可能为BCP熔体与不可渗透的固体接触的自组装提供了新的视角。克服了聚合物链构象熵损失的大量固相接触，即使在（良好）溶剂气氛中，也可以防止结构松弛到其平衡状态（即，形成微区结构）。我们的结果提供了BCP的长寿命非平衡结构的直接实验证据，并且可能为BCP熔体与不可渗透的固体接触的自组装提供了新的视角。

更新日期：2018-01-10

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