Rich Variety of Three-Dimensional Nanostructures Enabled by Geometrically Constraining Star-like Block Copolymers.
Rich Variety of Three-Dimensional Nanostructures Enabled by Geometrically Constraining Star-like Block Copolymers.
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DOI：
10.1021/acs.langmuir.6b01904
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发表时间：
2016-07
期刊：
影响因子：
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通讯作者：
Chao Wang;Yuci Xu;Weihua Li;Zhiqun Lin
中科院分区：
文献类型：
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作者：
Chao Wang;Yuci Xu;Weihua Li;Zhiqun Lin
在圆柱约束下，星形结构对星形嵌段共聚物相行为的影响与体约束（即非约束）有很大不同。在四种情况下(分别为：ϕA = 0.3和V0 bb0；采用自洽平均场理论的伪谱方法首次考察了柱面约束的孔壁偏向于内部A块（即A-优先）和B块（即B-优先）。令人惊讶的是，在星状（AB）3二嵌段共聚物中，在ϕA = 0.3和V0 >时，观察到一种新的纳米相，即圆柱上穿孔片层（表示PC）。随着f的进一步增大，发现单个薄片（记为L1）具有更大的相区。在a优先壁（即V0 0）的约束下，大量形成倒圆柱体，PC相趋于稳定，其自由能随f的增大而减小，表明在此条件下PC相倾向于形成。此外，与C1→L1→PC （C1，单圆柱微畴）在ϕA = 0.3和V0 >时的相变形成鲜明对比的是，当受到a优先壁（ϕA = 0.7）时，由于双层结构的形成，确定了不同的相变顺序（即C1→PC→L1）。在我们的计算的基础上，我们完全理解了在施加的圆柱形约束下星形结构对（AB）f二嵌段共聚物的影响，特别是作为f函数的相边界的移动。这些自组装的纳米结构有望应用于纳米线、光子晶体和纳米技术的光刻模板。
The influence of star-like architecture on phase behavior of star-like block copolymer under cylindrical confinement differs largely from the bulk (i.e., nonconfinement). A set of intriguing self-assembled morphologies and the corresponding phase diagrams of star-like (AB)f diblock copolymers with different numbers of arms f (i.e., f = 3, 9, 15, and 21) in four scenarios (ϕA = 0.3 and V0 > 0; ϕA = 0.3 and V0 0; and ϕA = 0.7 and V0 0 represent that the pore wall of cylindrical confinement prefers the inner A block (i.e., A-preferential) and B block (i.e., B-preferential), respectively) were for the first time scrutinized by employing the pseudospectral method of self-consistent mean-field theory. Surprisingly, a new nanoscopic phase, that is, perforated-lamellae-on-cylinder (denoted PC), was observed in star-like (AB)3 diblock copolymer at ϕA = 0.3 and V0 > 0. With a further increase in f, a single lamellae (denoted L1) was found to possess a larger phase region. Under the confinement of A-preferential wall (i.e., V0 0, where an inverted cylinder was formed in bulk, the PC phase became stable, and its free energy decreased as f increased, suggesting the propensity to form PC phase under this condition. Moreover, in stark contrast to the phase transition of C1 → L1 → PC (C1, a single cylindrical microdmain) at ϕA = 0.3 and V0 > 0, when subjected to the A-preferential wall (ϕA = 0.7), a different phase transition sequence (i.e., C1 → PC → L1) was identified due to the formation of a double-layer structure. On the basis of our calculations, the influence of star-like architecture on (AB)f diblock copolymer under the imposed cylindrical confinement, particularly the shift of the phase boundaries as a function of f, was thoroughly understood. These self-assembled nanostructures may hold the promise for applications as lithographic templates for nanowires, photonic crystals, and nanotechnology.