Guo Qing-Hui, Jia Manping, Liu Zhichang, Qiu Yunyan, Chen Hongliang, Shen Dengke, Zhang Xuan, Tu Qing, Ryder Matthew R, Chen Haoyuan, Li Peng, Xu Yaobin, Li Penghao, Chen Zhijie, Shekhawat Gajendra S, Dravid Vinayak P, Snurr Randall Q, Philp Douglas, Sue Andrew C-H, Farha Omar K, Rolandi Marco, Stoddart J Fraser
Department of Electrical and Computer Engineering, University of California, Santa Cruz, California 95064, United States.
School of Science, Westlake University, 18 Shilongshan Road, Hangzhou 310024, China.
J Am Chem Soc. 2020 Apr 1;142(13):6180-6187. doi: 10.1021/jacs.9b13790. Epub 2020 Feb 19.
The efficient preparation of single-crystalline ionic polymers and fundamental understanding of their structure-property relationships at the molecular level remains a challenge in chemistry and materials science. Here, we describe the single-crystal structure of a highly ordered polycationic polymer (polyelectrolyte) and its proton conductivity. The polyelectrolyte single crystals can be prepared on a gram-scale in quantitative yield, by taking advantage of an ultraviolet/sunlight-induced topochemical polymerization, from a tricationic monomer-a self-complementary building block possessing a preorganized conformation. A single-crystal-to-single-crystal photopolymerization was revealed unambiguously by in situ single-crystal X-ray diffraction analysis, which was also employed to follow the progression of molecular structure from the monomer, to a partially polymerized intermediate, and, finally, to the polymer itself. Collinear polymer chains are held together tightly by multiple Coulombic interactions involving counterions to form two-dimensional lamellar sheets (1 nm in height) with sub-nanometer pores (5 Å). The polymer is extremely stable under 254 nm light irradiation and high temperature (above 500 K). The extraordinary mechanical strength and environmental stability-in combination with its impressive proton conductivity (∼3 × 10 S cm)-endow the polymer with potential applications as a robust proton-conducting material. By marrying supramolecular chemistry with macromolecular science, the outcome represents a major step toward the controlled synthesis of single-crystalline polyelectrolyte materials with perfect tacticity.
在化学和材料科学领域，高效制备单晶离子聚合物并从分子层面深入理解其结构-性能关系仍是一项挑战。在此，我们描述了一种高度有序的聚阳离子聚合物（聚电解质）的单晶结构及其质子传导率。利用紫外光/阳光诱导的拓扑化学聚合反应，从一种三价阳离子单体（一种具有预组织构象的自互补结构单元）出发，可定量高产率地制备克级规模的聚电解质单晶。原位单晶X射线衍射分析明确揭示了单晶到单晶的光聚合过程，该分析还用于追踪分子结构从单体到部分聚合中间体，最终到聚合物本身的演变。共线的聚合物链通过涉及抗衡离子的多重库仑相互作用紧密结合在一起，形成具有亚纳米级孔隙（5 Å）的二维层状薄片（高度为1 nm）。该聚合物在254 nm光照射和高温（高于500 K）下极其稳定。其非凡的机械强度和环境稳定性，再加上令人印象深刻的质子传导率（约3×10 S cm），使该聚合物有望作为一种坚固的质子传导材料得到应用。通过将超分子化学与高分子科学相结合，这一成果朝着可控合成具有完美规整度的单晶聚电解质材料迈出了重要一步。
