The Development of Main-Chain Interlocked Macromolecules

链烷和轮烷由两种或两种以上独立的组分组成，这些组分通过机械或拓扑键联锁在一起并固定在一起。这些物种的大分子版本特别有趣，因为它们提供了新的聚合物结构来探索。互锁的大分子结构，如聚[n]链烷和聚[3]轮烷具有机械键作为聚合物主链的组成部分，这应该赋予这些材料不同寻常的性能。例如，它们能够在不显著改变键合或扭转角度的情况下扩展/收缩，因此，控制这种运动的能力可能会导致新的大分子致动器。此外，预测这种结构具有非常大的模量损失、低的粘性流动活化能和快速的应力松弛等不寻常的粘弹性特性。美国国家科学基金会化学部的大分子、超分子和纳米化学项目支持凯斯西储大学Rowan教授的研究小组开发新的合成方案，以实现这些有趣的大分子。该合成方法利用金属配位作为聚合步骤和不同共价“固定”步骤的热力学驱动力，以获得聚[n]链烷或聚[3]轮烷。拟议的研究是化学领域内不同学科的真正混合，综合研究方法将为高中，本科和研究生水平的学生提供广泛的研究教育基础。外展活动旨在增加科学和工程领域代表性不足的少数民族的比例，整合研究和教育，提供令人兴奋的学习环境，并为学生研究人员创造教学机会。其中一部分是由罗文集团发起的成功外展项目的扩展和发展，例如“自然材料”项目，这是克利夫兰自然历史博物馆马丁路德金日发现日的一部分。

Catenanes and rotaxanes consist of two or more separate components that are interlocked together and held in place by the mechanical or topological bond. Macromolecular versions of these species are especially intriguing as they offer new polymeric architectures to explore. Interlocked macromolecular structures such as poly[n]catenanes and poly[3]rotaxanes have the mechanical bond as an integral part of the polymer backbone which should impart unusual properties on these materials. For example, they have the ability to expand/contract without significantly altering bond or torsion angles and as such, the ability to control such motions could result in new macromolecular actuators. Furthermore, unusual viscoelastic properties, e.g. very large modulus loss, low activation energy for viscous flow and rapid stress relaxation, are all predicted for such structures. The Macromolecular, Supramolecular and Nanochemistry Program of the Chemistry Division of the National Science Foundation supports the research group of Prof. Rowan of Case Western Reserve University to develop novel synthetic protocols to allow access to these interesting macromolecules. The synthetic approach utilizes metal-ligand coordination as the thermodynamic driving force for the polymerization step and different covalent 'fixing' steps to access either the poly[n]catenanes or poly[3]rotaxanes. The proposed research is truly a mix of different disciplines within the chemistry arena and the integrated research approach will provide students, at high-school, undergraduate and graduate levels, a broad research education base. The outreach activities are designed to increase the fraction of underrepresented minorities in science and engineering, integrate research and education, provide an exciting learning environment, and create teaching opportunities for the student researchers. Part of this is the expansion and growth of successful outreach programs initiated by the Rowan group, for example the "Natures Materials" program which is part of the Cleveland Museum of Natural History's MLK day Discovery Day.