Precisely Encoding Geometric Features into Discrete Linear Polymer Chains for Robust Structural Engineering
Precisely Encoding Geometric Features into Discrete Linear Polymer Chains for Robust Structural Engineering
复制标题
将几何特征精确编码到离散线性聚合物链中，以实现稳健的结构工程
DOI：
10.1021/jacs.1c09575
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发表时间：
2021
影响因子：
15
通讯作者：
Dong Xue-Hui
中科院分区：
文献类型：
--
作者：
Zhou Dongdong;Xu Miao;Ma Zhuang;Gan Zhanhui;Tan Rui;Wang Shuai;Zhang Zhengbiao;Dong Xue-Hui
分子形状是调节自组织和识别过程的重要参数，由于缺乏精确有效的调节方法，分子形状在嵌段聚合物中尚未得到充分认识和利用。这项工作（i）开发了一种稳健的方法，通过将几何特征引入到其他均质链中来打破线性聚合物的固有对称性，并且（ii）定量地强调了分子几何/结构对自组装行为的关键贡献。根据预先设计的序列迭代连接不同侧链的同源单体，生成具有精确化学结构、均匀链长和沿着主链的可编程侧链梯度的离散聚合物，该聚合物可转录成不同的形状。精确的化学消除了所有缺陷和异质性，为分子几何作用的基本研究提供了一个精致的平台。在这些严格的单组分系统中捕获了丰富的非常规复杂相，包括 Frank–Kasper A15 和 σ 相以及十二角准晶相。自组装行为对几何形状的细微变化非常敏感，因此简单地在侧链之间迁移一些亚甲基单元就会产生晶格尺寸或相稳定性的显着差异，甚至引发向不同结构的相变。这种现象可以用几何论证来合理化，即不均匀的侧链分布会导致两个不混溶嵌段之间的构象失配，从而导致不同的界面曲率和不同的晶格对称性。这一深远的贡献表明，分子几何形状是结构工程的有效且稳健的参数。
Molecular shape is an essential parameter that regulates the self-organization and recognition process, which has not yet been well appreciated and exploited in block polymers due to the lack of precise and efficient modulation methods. This work (i) develops a robust approach to break the intrinsic symmetry of linear polymers by introducing geometric features into otherwise homogeneous chains and (ii) quantitatively highlights the critical contribution of molecular geometry/architecture to the self-assembly behaviors. Iteratively connecting homologous monomers of different side chains according to pre-designed sequences generates discrete polymers with exact chemical structure, uniform chain length, and programmable side-chain gradient along the backbone, which transcribes into diverse shapes. The precise chemistry eliminates all the defects and heterogeneities, providing a delicate platform for fundamental inquiries into the role of molecular geometry. A rich collection of unconventional complex phases, including Frank–Kasper A15 and σ phases, as well as a dodecagonal quasicrystal phase, were captured in these rigorous single-component systems. The self-assembly behaviors are strikingly sensitive to subtle variations of geometry, such that simply migrating a few methylene units among the side chains would generate substantial differences in lattice size or phase stability, or even trigger a phase transition toward distinct structures. The phenomena can be rationalized with a geometric argument that nonuniform side chain distribution leads to conformational mismatch between two immiscible blocks, resulting in varied interfacial curvatures and distinct lattice symmetries. The profound contribution demonstrates that molecular geometry is an effective and robust parameter for structural engineering.