Liu Zhongguo, Yang Ze, Chen Xin, Tan Rui, Li Gang, Gan Zhanhui, Shao Yu, He Jinlin, Zhang Zhengbiao, Li Weihua, Zhang Wen-Bin, Dong Xue-Hui
South China Advanced Institute for Soft Matter Science and Technology, School of Molecular Science and Engineering, South China University of Technology, Guangzhou 510640, China.
Key Laboratory of Polymer Chemistry & Physics of Ministry of Education, Center for Soft Matter Science and Engineering, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
JACS Au. 2020 Dec 9;1(1):79-86. doi: 10.1021/jacsau.0c00014. eCollection 2021 Jan 25.
As size-amplified analogues of canonical macromolecules, polymeric chains built up by "giant" monomers represent an experimental realization of the "beads-on-a-string" model at larger length scales, which could provide insights into fundamental principles of polymer science. In this work, we modularly constructed discrete giant polymeric chains using nanosized building blocks (polyhedral oligomeric silsesquioxane, POSS) as basic repeat units through an efficient and robust iterative exponential growth approach, with precise control on molecular parameters, including size, composition, regioconfiguration, and surface functionalities. Their chemical structures were fully characterized by nuclear magnetic resonance spectroscopy, size-exclusion chromatography, and matrix-assisted laser desorption ionization time-of-flight mass spectrometry. With elaborately designed amphiphilic block POSS chains and their analogues made of conventional monomers, the size effects were delicately studied and highlighted. Interesting assembly behaviors emerge as a result of distinct interactions and molecular dynamics. This category of molecules shares general self-assembly characteristics as the conventional counterparts in terms of phase transition and evolution. Meanwhile, it turns out that the monomer size has profound impacts on phase stability, as a trade-off between entropic and enthalpic contributions. It may open up a door for modular and programmable design of interesting materials with complex structures and diverse functions.
作为典型大分子的尺寸放大类似物，由“巨型”单体构建的聚合物链代表了“串珠”模型在更大长度尺度上的实验实现，这可为聚合物科学的基本原理提供见解。在这项工作中，我们通过一种高效且稳健的迭代指数生长方法，使用纳米级构建块（多面体低聚倍半硅氧烷，POSS）作为基本重复单元，模块化地构建离散的巨型聚合物链，并对包括尺寸、组成、区域构型和表面功能在内的分子参数进行精确控制。通过核磁共振光谱、尺寸排阻色谱和基质辅助激光解吸电离飞行时间质谱对其化学结构进行了全面表征。通过精心设计的两亲性嵌段POSS链及其由传统单体制成的类似物，对尺寸效应进行了细致研究并突出显示。由于独特的相互作用和分子动力学，出现了有趣的组装行为。这类分子在相变和演化方面与传统分子具有一般的自组装特性。同时，事实证明单体尺寸对相稳定性有深远影响，这是熵贡献和焓贡献之间的权衡。它可能为具有复杂结构和多样功能的有趣材料的模块化和可编程设计打开一扇门。
