Design and Synthesis of New Interlocked Polymers

在化学学部（CHE）的大分子、超分子和纳米化学（MSN）项目和材料研究学部（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]链烷和聚[n]轮烷的合成方法。链烷和轮烷由两种或两种以上的组分组成，它们相互连接并通过机械键固定在一起。链式烷由互锁的环组成，而轮烷则由一个环与一个哑铃（一种丝状分子，两端都有足够大的塞，以防止环脱线）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能。虽然已经制备了聚[2]链烷和主链聚[n]轮烷等结构，但聚[n]链烷和双螺纹滑环凝胶的合成方法却很少受到关注。在这种结构中，机械键是聚合物骨架的一部分，允许大分子在没有显著活化能的情况下膨胀/收缩。因此，这种聚合物可以表现出不同寻常的粘弹性。这项研究将探索新的合成方案，将允许访问这些有趣的大分子。拟议的研究将混合化学领域内的不同学科，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个层次的学生提供涵盖这些主题的广泛教育经验。此外，高中和本科的综合研究和推广活动将旨在增加科学和工程领域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芝加哥南部的高中生。本研究将重点开发基于链烷和轮烷的新型联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先组织有机组分的合成方法上，然后通过闭合环的复分解来获得聚[n]链烷的共价固定，或者通过高产、无催化剂的点击化学来获得双线滑动环凝胶。该项目还将对建筑构件的结构如何影响产品分布、分子量以及这些独特聚合物的最终性能进行系统的研究。与这项工作相关的结果有可能通过解决聚合物系统中机械连接的基本问题来推进聚合物化学。此外，双线滑动环凝胶有望引起广泛的科学兴趣，因为它们既可以作为被困缠结的网络模型，也可以作为具有不同寻常的机械和功能特性的材料的潜在来源。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 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.