Complex Phase Behavior in Particle-Forming AB/AB′ Diblock Copolymer Blends with Variable Core Block Lengths
Complex Phase Behavior in Particle-Forming AB/AB′ Diblock Copolymer Blends with Variable Core Block Lengths
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DOI：
10.1021/acs.macromol.1c01290
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发表时间：
2021-08
期刊：
影响因子：
5.5
通讯作者：
A. Lindsay;G. K. Cheong;Austin J. Peterson;S. Weigand;K. Dorfman;T. Lodge;F. Bates
中科院分区：
文献类型：
--
作者：
A. Lindsay;G. K. Cheong;Austin J. Peterson;S. Weigand;K. Dorfman;T. Lodge;F. Bates
在过去的十年中，大量的复杂性已被报道在填充的组成不对称的，颗粒形成的二嵌段共聚物熔体，开始与Frank-Kasper σ相的发现，并继续与随后的发现的十二方准晶和C14，C15，和A15相。首先确定的自洽平均场理论（SCFT），共混二嵌段共聚物已被证明是一个有用的策略，在扩展这些包装新的化学和长度尺度。然而，在混合两种共聚物时产生的巨大相空间的大部分仍然未被探索。在此，我们扩大我们以前的工作调查聚苯乙烯-嵌段-1，4-聚丁二烯二嵌段共聚物的二元共混物，专注于二元混合物具有恒定的电晕（多数）块长度和一系列的核心（少数）块长度的比例。小角X射线散射和透射电子显微镜进行了5个窄分散度的二嵌段共聚物和相关的共混物发现了丰富的相空间，包括12个不同的纳米结构。值得注意的是，与SCFT预测一致，我们记录了在高分子量和低分子量组分的混合物中较大共聚物的低分数处的C14 Laves相。然而，实验和SCFT计算表明，该窗口被截断时，较小的共聚物是弱隔离紧密堆积。此外，我们发现，即使是适度的差异，在核心块长度是足以稳定的σ相，突出的影响，核心块分散在以前的研究，以及在访问这些复杂的颗粒相的效用的共混。
Over the past decade, a wealth of complexity has been reported in the packing of compositionally asymmetric, particle-forming diblock copolymer melts, beginning with the discovery of the Frank–Kasper σ phase and continuing with subsequent discoveries of a dodecagonal quasicrystal and the C14, C15, and A15 phases. First identified by self-consistent mean-field theory (SCFT), blending diblock copolymers has proven to be a useful strategy in extending these packings to new chemistries and length scales. However, much of the immense phase space created on blending two copolymers remains unexplored. Herein, we expand on our previous work investigating binary blends of polystyrene-block-1,4-polybutadiene diblock copolymers, focusing on binary mixtures with a constant corona (majority) block length and a range of ratios of core (minority) block lengths. Small-angle X-ray scattering and transmission electron microscopy conducted with 5 narrow dispersity diblock copolymers and the associated blends uncovered a rich phase space including 12 distinct nanostructures. Notably, in agreement with SCFT predictions, we document a C14 Laves phase at low fractions of the larger copolymer in a mixture of high and low molecular weight components. However, experiments and SCFT calculations reveal that this window is truncated by close packing when the smaller copolymer is weakly segregated. Moreover, we find that even a modest difference in core block lengths is sufficient to stabilize the σ phase, highlighting the impact of core block dispersity in previous studies as well as the utility of blending in accessing these complex particle phases.