Collaborative Research: Mechanochemistry of Metallocenes

化学系的大分子、超分子和纳米化学项目将资助南卡罗来纳大学的唐传兵教授和杜克大学的斯蒂芬·l·克雷格教授开发一种新型聚合物（塑料），这种聚合物可以对特定类型的应力做出反应。合成聚合物用途广泛，可加工，重量轻，并具有可调的机械性能，使其在日常生活中很有用。这些由Tang团队制造的含金属聚合物被用于制造对物理压力有反应但在高温下稳定的聚合物材料。该团队的研究探索了机械化学控制塑料的设计和潜在用途。这些塑料可以通过物理操作而不是重新熔化来回收，最终在重复使用期间节省能源。外展活动包括Chem-STAR计划，该计划为罗利-达勒姆地区的主要本科院校提供研究资源。经济困难和少数族裔学生也可以通过南卡罗来纳大学的美国化学学会项目SEED暑期研究项目获得指导，并接触到前沿研究。本项目主要研究含茂金属主链聚合物的合成方法及其机械化学反应性。本研究计划利用开环复分解聚合合成具有良好定义的主链茂金属聚合物和共聚物。茂金属机械化学的实验表征是通过结合最先进的聚合物声化学和单分子力谱技术进行的。在聚合物中茂金属的不稳定性进一步研究使用计算模型，模拟在分子水平上施加的力。为了在分子尺度上阐明剥离和剪切的相对作用，进行了机理研究。本研究的首要目标是了解金属-环戊二烯键高选择性机械化学断裂的机制和构效关系。这项工作有可能开发出具有机械响应性和热稳定性的合成聚合物，这两者对于大多数商品聚合物的可重复使用和可回收性都很重要。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

With this award, the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry is funding Professor Chuanbing Tang of the University of South Carolina and Professor Stephen L. Craig of Duke University to develop a new class of polymers (plastics) that respond to specific types of stress. Synthetic polymers are versatile, processable, light weight, and have tunable mechanical properties, making them useful in everyday life. These metal-containing polymers made by the Tang group are used to make polymer materials that respond to physical pressures but are stable at high temperatures. The team's research explores the design and potential uses of mechanochemically-controlled plastics. Such plastics may be recycled by physical manipulation rather than re-melting, ultimately resulting in energy-savings during reuse. Outreach activities include the Chem-STAR program that provides research resources to primarily undergraduate institutions in the Raleigh-Durham area. Economically disadvantaged and minority students are also mentored and exposed to cutting-edge research through American Chemical Society Project SEED summer research program at the University of South Carolina. This project is focused on developing synthetic approaches toward main-chain metallocene-containing polymers and studying their mechanochemical reactivity. The research plan utilizes ring-opening metathesis polymerization to synthesize well-defined main-chain metallocene polymers and copolymers. Experimental characterization of metallocene mechanochemistry is carried out through a combination of state-of-the-art techniques in polymer sonochemistry and single molecule force spectroscopy. Metallocene lability in polymers is further investigated using computational models that simulate forces applied at the molecular level. Mechanistic studies are conducted in order to elucidate the relative contribution of peeling versus shearing at the molecular scale. The overarching goal of this work is to understand the mechanisms and structure-activity relationship underlying the highly selective mechanochemical scission of metal-cyclopentadienyl bond. This work has the potential to develop synthetic polymers that are mechanically responsive and thermally stable, both of which are important for reusability and recyclability of most commodity polymers.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.