The Development of Main-Chain Interlocked Macromolecules

链烷和轮烷由两个或两个以上相互关联的独立组分组成，并通过机械键或拓扑键固定在适当的位置。这些物种的大分子版本特别耐人寻味，因为它们提供了新的聚合物体系结构供探索。互锁的大分子结构，如聚[n]链烷和聚[3]轮烷，具有作为聚合物主链组成部分的机械键，这将赋予这些材料特殊的性质。例如，它们能够在不显著改变成键或扭转角度的情况下膨胀/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，还预测了此类结构的异常粘弹性性质，例如非常大的模数损失、低的粘性流动活化能和快速的应力松弛。国家科学基金会化学部的大分子、超分子和纳米化学计划支持凯斯西储大学罗文教授的研究小组开发新的合成方案，以允许访问这些有趣的大分子。该合成方法利用金属-配体配位作为聚合步骤的热力学驱动力，并利用不同的共价固定步骤来获得聚[n]环烷或聚[3]轮烷。拟议的研究确实是化学领域不同学科的混合，综合研究方法将为高中、本科生和研究生提供广泛的研究教育基础。外展活动的目的是增加科学和工程领域代表性不足的少数族裔的比例，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。部分原因是由Rowan集团发起的成功的外展计划的扩大和增长，例如作为克利夫兰自然历史博物馆MLK日发现日的一部分的“自然材料”计划。

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.