Design and Synthesis of New Interlocked Polymers

在化学部（CHE）的大分子、超分子和纳米化学（MSN）项目和材料研究部（DMR）的聚合物项目的支持下，芝加哥大学的Stuart J. Rowan教授正在开发制备聚[n]索烃和聚[n]轮烷的合成方法。 链烷和轮烷由两个或多个互锁在一起并通过机械键保持在适当位置的组分组成。 链烷烃由互锁的环组成，而轮烷由与哑铃形（在任一端具有足够大以防止环脱螺纹的塞子的线状分子）组分互锁的环组成。 这些物种的大分子或聚合物版本特别有趣，因为它们提供了新的聚合物结构，其中不同组分的相对运动允许获得新的和独特的性质。 虽然已经制备了诸如聚[2]索烃和主链聚[n]轮烷的结构，但是聚[n]索烃和双螺纹滑环凝胶的合成方法受到的关注少得多。 在这样的结构中，机械键是聚合物主链的一部分，并且允许大分子膨胀/收缩而没有显著的活化能。因此，这样的聚合物可以表现出不寻常的粘弹性能。 这项研究将探索新的合成方案，以获得这些有趣的大分子。 拟议的研究将混合化学竞技场内的不同学科，从合成有机和金属配位化学到聚合物科学和表征。这种综合研究方法将为各级学生提供涵盖这些主题的广泛教育经验。此外，综合高中和本科研究和推广活动将旨在增加科学和工程中代表性不足的少数民族的比例。具体来说，计划中的活动将涉及来自芝加哥南部的高中生。 这项研究将集中于开发基于索烃和轮烷的新型互锁聚合物的合成路线。 重点将放在利用金属配体配位作为热力学驱动力来预组织有机组分的合成方法上，然后通过闭环复分解来获得聚[n]索烃，或通过高产、无催化剂的点击化学来获得双螺纹滑环凝胶的共价固定。 该项目还将系统地研究如何利用建筑部件的结构来影响这些独特聚合物的产品分布、分子量以及由此产生的性能。 与这项工作相关的结果有可能通过解决聚合物体系中机械连接的基本问题来推进聚合物化学。 此外，双螺纹滑环凝胶预计将具有广泛的科学意义，因为它们既可以作为具有捕获缠结的网络模型，也可以作为具有不寻常机械和功能特性的材料的潜在来源。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估来支持。

With the support of the Macromolecular, Supramolecular and Nanochemistry (MSN) program in the Division of Chemistry (CHE) and the Polymers program in the Division of Materials Research (DMR), Professor Stuart J. Rowan of the University of Chicago is developing synthetic methodologies for the preparation of poly[n]catenanes and poly[n]rotaxanes. Catenanes and rotaxanes consist of two or more components that are interlocked together and held in place by the mechanical bond. Catenanes are comprised of interlocked rings while rotaxanes consist of a ring that is interlocked with a dumbbell (a thread-like molecule with stoppers on either end large enough to prevent dethreading of the ring) component. Macromolecular or polymeric versions of these species are particularly intriguing as they offer new polymeric architectures in which the relative motions of the different components allow access to new and unique properties. While architectures such as poly[2]catenanes and main-chain poly[n]rotaxanes have been prepared, synthetic methodologies to poly[n]catenanes and doubly threaded slide ring gels have received much less attention. In such architectures, the mechanical bond is part of the polymer backbone and allows the macromolecules to expand/contract without significant activation energy. As a result, such polymers can exhibit unusual viscoelastic properties. This research will explore new synthetic protocols that will allow access to these intriguing macromolecules. The proposed research will mix different disciplines within the chemistry arena, from synthetic organic and metal coordination chemistry to polymer science and characterization. This integrated research approach will provide students at all levels with broad educational experiences covering these topics. Additionally, the integrated high school and undergraduate research and outreach activities will be designed to increase the fraction of underrepresented minorities in science and engineering. Specifically, the planned activities will involve high school students from Chicago’s south side. This research will focus on developing synthetic routes to new interlocked polymers based on catenanes and rotaxanes. A strong emphasis will be placed on synthetic methodologies that utilize metal-ligand coordination as the thermodynamic driving force to preorganize the organic components, followed by a covalent fixing either through ring-closing metathesis to access the poly[n]catenanes, or high-yielding, catalyst-free click chemistries to access the doubly-threaded slide ring gels. This project will also provide systematic investigation on how the structure of the building components can be used to impact product distribution, molecular weight, as well as the resulting properties of these unique polymers. Results associated with this work have the potential to advance polymer chemistry by addressing fundamental questions about mechanical linkages in polymeric systems. Moreover, doubly-threaded slide ring gels are expected to be of broad scientific interest as they serve both as models of networks with trapped entanglements as well as potential sources of materials with unusual mechanical and functional properties.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.