Nian Shifeng, Lian Huada, Gong Zihao, Zhernenkov Mikhail, Qin Jian, Cai Li-Heng
Department of Chemical Engineering, Stanford University, Stanford, California 94305, United States.
National Synchrotron Light Source-II, Brookhaven National Laboratory, Upton, New York 11973, United States.
ACS Macro Lett. 2019 Nov 19;8(11):1528-1534. doi: 10.1021/acsmacrolett.9b00721. Epub 2019 Nov 1.
Linear-bottlebrush-linear (LBBL) triblock copolymers represent an emerging system for creating multifunctional nanostructures. Their self-assembly depends on molecular architecture but remains poorly explored. We synthesize polystyrene--bottlebrush polydimethylsiloxane--polystyrene triblock copolymers with controlled molecular architecture and use them as a model system to study the self-assembly of LBBL polymers. Unlike classical stiff rod-flexible linear block copolymers that are prone to form highly ordered nanostructures such as lamellae, at small weight fractions of the linear blocks, LBBL polymers self-assemble to a disordered sphere phase, regardless of the bottlebrush stiffness. Microscopically, characteristic lengths increase with the bottlebrush stiffness by a power of 2/3, which is captured by a scaling analysis. Macroscopically, the formed nanostructures are ultrasoft, reprocessable elastomers with shear moduli of about 1 kPa, two orders of magnitude lower than that of conventional polydimethylsiloxane elastomers. Our results provide insights on exploiting the self-assembly of LBBL polymers to create soft functional nanostructures.
线性-刷形-线性（LBBL）三嵌段共聚物是一种用于创建多功能纳米结构的新兴体系。它们的自组装取决于分子结构，但仍未得到充分研究。我们合成了具有可控分子结构的聚苯乙烯-刷形聚二甲基硅氧烷-聚苯乙烯三嵌段共聚物，并将其用作模型体系来研究LBBL聚合物的自组装。与容易形成高度有序纳米结构（如片层）的经典刚性棒-柔性线性嵌段共聚物不同，在线性嵌段的重量分数较小时，LBBL聚合物会自组装成无序的球形相，而与刷形链段的刚性无关。在微观层面上，特征长度随刷形链段的刚性以2/3的幂次增加，这一点通过标度分析得以体现。在宏观层面上，形成的纳米结构是超软的、可再加工的弹性体，其剪切模量约为1 kPa，比传统聚二甲基硅氧烷弹性体低两个数量级。我们的研究结果为利用LBBL聚合物的自组装来创建软功能纳米结构提供了见解。
