Department of Chemistry, Washington University, St. Louis, Missouri 63130, United States.
J Am Chem Soc. 2022 Jun 8;144(22):9990-9996. doi: 10.1021/jacs.2c03166. Epub 2022 May 26.
Mechanically interlocked molecules (MIMs) possess unique architectures and nontraditional degrees of freedom that arise from well-defined topologies that are achieved through precise mechanical bonding. Incorporation of MIMs into materials can thus provide an avenue to discover new and emergent macroscale properties. Here, the synthesis of a phenanthroline-based [2]catenane crosslinker and its incorporation into polyacrylate organogels are described. Specifically, Cu(I) metalation and demetalation was used as a postgelation strategy to tune the mechanical properties of a gel by controlling the conformational motions of integrated MIMs. The organogels were prepared via thermally initiated free radical polymerization, and Cu(I) metal was added in MeOH to the pretreated, swollen gels. Demetalation of the gels was achieved by adding lithium cyanide and washing the gels. Changes in Young's and shear moduli, as well as tensile strength, were quantified through oscillatory shear rheology and tensile testing. The reported approach provides a general method for postgelation tuning of mechanical properties using metals and well-defined catenane topologies as part of a gel network architecture.
机械互锁分子（MIMs）具有独特的结构和非传统的自由度，这些自由度源于通过精确机械键合实现的明确拓扑结构。将 MIMs 纳入材料中可以为发现新的和新兴的宏观性质提供途径。在这里，描述了一种基于菲咯啉的[2]轮烷交联剂的合成及其在聚丙烯酸酯有机凝胶中的掺入。具体来说，Cu（I）金属化和脱金属化被用作后凝胶化策略，通过控制集成的 MIM 的构象运动来调节凝胶的机械性能。通过热引发自由基聚合制备有机凝胶，并将 Cu（I）金属加入到预处理的、溶胀的凝胶中甲醇。通过加入氰化锂和洗涤凝胶来实现凝胶的脱金属化。通过动态剪切流变学和拉伸测试定量测量杨氏模量和剪切模量以及拉伸强度的变化。所报道的方法提供了一种使用金属和明确定义的轮烷拓扑结构作为凝胶网络结构的一部分来进行后凝胶化机械性能调谐的通用方法。
