作者：Xuan Yue, Zhen Geng, Nan Yan, Wei Jiang
关键字：分级自组装, 多隔室胶束, 嵌段共聚物混合物, 二维受限, 协同效应
论文来源：期刊
具体来源：Physical Chemistry Chemical Physics, 2020, 22(3), 1194-1203
发表时间：2020年

摘要：分级自组装为构建形貌和内部结构精确可控的复杂材料提供了优雅且节能的自下而上策略。本文通过聚苯乙烯-b-聚4-乙烯基吡啶（PS-b-P4VP）和聚苯乙烯-b-聚N-异丙基丙烯酰胺（PS-b-PNIPAM）嵌段共聚物混合物在THF/水混合溶剂中的分级自组装，轻松制备了蛹状多隔室胶束（MCMs），这些结构无法由任一单独嵌段共聚物获得，表明分级自组装是两种BCPs协同作用的结果。动力学研究表明，MCMs由PS-b-P4VP/PS-b-PNIPAM混合物共组装形成的小球形胶束（SSMs）经分级自组装而成。随后研究了PS-b-P4VP/PS-b-PNIPAM混合溶液在阳极氧化铝（AAO）模板纳米孔中的自组装，在二维受限下获得了具有周期多层结构的长多隔室胶束（LMCMs）。根据预成型SSMs二次组装活性，纳米孔对分级自组装的受限效应可分为动态受限和静态受限两种情况：动态受限可影响SSMs布朗运动并促进其融合形成更大球形胶束；当AAO纳米孔部分填充预成型SSMs时，静态受限可降低BCP链沿LMCMs短轴的拉伸，诱导长程有序多层纳米结构形成。这些结果表明协同效应在BCPs分级组装中发挥重要作用，同时可通过圆柱受限进一步调控BCP组装的纳米结构和尺寸。

Abstract：Hierarchical self-assembly offers an elegant and energy-efficient bottom-up strategy for the fabrication of complex materials with precisely controllable morphologies and internal structures. Herein, pupa-like multicompartment micelles (MCMs) were readily fabricated via the hierarchical self-assembly of a polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) and polystyrene-block-poly(N-isopropylacrylamide) (PS-b-PNIPAM) block copolymer mixture in a THF/water mixture solvent, which were unable to be obtained by any of the individual block copolymers (BCPs). This means that the hierarchical self-assembly is a result of the synergistic cooperation between the two BCPs. Moreover, a kinetic study revealed that the MCMs were formed by hierarchical self-assembly of small spherical micelles (SSMs), which were co-assembled from the PS-b-P4VP/PS-b-PNIPAM mixture. Subsequently, we investigated the self-assembly of a PS-b-P4VP/PS-b-PNIPAM mixed solution confined in the nanopores of an anodic aluminum oxide (AAO) template. In such two-dimensional confinement, long multicompartment micelles (LMCMs) with a periodic multilayer structure were obtained. Notably, the confinement effect of nanopores on the hierarchical self-assembly could be distinguished into dynamic and static confinement according to the activity of secondary assembly of the preformed SSMs. The dynamic confinement can affect the Brownian movement of SSMs and thus promotes their fusion to form spherical micelles with larger size. For the situation where AAO nanopores were partially filled with the preformed SSMs, the static confinement could decrease the stretching of BCP chains along the short axis of LMCMs and induce the formation of long-range ordered multilayer nanostructures. These results illustrated that the synergistic effect played an important role in the hierarchical assembly of BCPs, and such hierarchical self-assembly could be further manipulated by cylindrical confinement to rationally tune the nanostructures and dimensions of the BCP assemblies.

论文链接：https://doi.org/10.1039/c9cp05180e