Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
J Phys Chem B. 2020 Dec 17;124(50):11519-11529. doi: 10.1021/acs.jpcb.0c07941. Epub 2020 Dec 3.
The characteristics of a new architecture of bottlebrush copolymers (BBCPs) self-assembly were studied using self-consistent field theory. In this molecule, a series of AB linear diblock side chains were connected at the diblock junction using a C backbone. The control over the linker length and its chemical nature created an additional constraint on the intrinsic AB diblock microphase separation. Increasing side-chain crowding by increasing the grafting density and total degree of polymerization induced improved phase separation. This was reflected in the overall reduction in the effective interaction parameter between the diblocks as well as the abrupt increase in phase density when crossing the order-disorder transition. Side-chain crowding resulted in an increase in the equilibrium domain spacing compared to a linear diblock. On the other hand, the localization of block C at the AB interface generated a diffuse domain boundary and reduction in side-chain stretching. The unique behavior of BBCPs was observed in 1D confined systems where the molecule showed the natural tendency to orient domains parallel to neutral confinement in contrast to the behavior of confined diblocks. Such behavior largely depended on the degree of incompatibility between the AB blocks and BBCP structure. A ternary phase diagram was constructed for different proportions of each block. Rich morphologies of core-shell domains and tiling patterns were observed including octagonal and pentagonal polygons. The unique architecture of this bottlebrush molecule and its improved nanoscale properties make it an attractive candidate for various applications of nanotechnology.
使用自洽场理论研究了新型刷型共聚物（BBCP）自组装的结构特点。在这种分子中，一系列 AB 线性嵌段侧链通过 C 主链连接在嵌段连接处。通过控制连接体的长度和化学性质，对固有 AB 嵌段微相分离施加了额外的约束。通过增加接枝密度和总聚合度来增加侧链拥挤度，诱导了更好的相分离。这反映在有效嵌段间相互作用参数的整体减小以及在越过有序-无序转变时相密度的突然增加。与线性嵌段相比，侧链拥挤导致平衡域间距增加。另一方面，C 嵌段在 AB 界面的定位产生了弥散的畴边界和侧链拉伸的减少。在一维受限体系中观察到 BBCP 的独特行为，其中分子表现出与中性受限平行取向的自然趋势，这与受限嵌段的行为形成对比。这种行为在很大程度上取决于 AB 嵌段之间的不相容程度和 BBCP 结构。为每个嵌段的不同比例构建了三元相图。观察到了丰富的核壳畴形态和平铺模式，包括八边形和五边形多边形。这种刷型分子的独特结构及其改进的纳米特性使其成为纳米技术各种应用的有吸引力的候选者。
