Doubly-Threaded Polycatenanes and Polyrotaxanes

有了这个奖项，化学系的大分子、超分子和纳米化学项目资助了芝加哥大学的Stuart J. Rowan博士开发合成方法来构建新的聚合物结构，并研究这些结构如何影响聚合物的性能。通常，聚合物或长链分子是由碳-碳共价键连接在一起的小分子制备的。共价键发生在电子对被原子共享时，它构成了所有有机化学的基本构建原则。这项工作中的方法是相当独特的，因为目标聚合物中的重复单元彼此之间不是共价键，但除非发生共价键断裂，否则无法分离。从本质上讲，单体单元像金属链或项链上的单个部件一样相互连接在一起。两个环环相扣的环的分子形式被称为连环烷，当它们在一起时，整体结构是聚连环烷（看起来像金属链）。一种相关的互锁聚合物，其中一个长聚合物分子穿过一个环状分子，就像绳子上的珠子一样，被称为聚轮烷。这种互锁聚合物材料在分子电子学、能量吸收材料、纳米记录和光学生物成像等领域具有独特的物理性能和潜在的应用前景。与该奖项相关的活动增加了广泛的参与，并使高中生、本科生和研究生在合成有机化学和聚合物化学方面得到培训。“自然材料”外展项目是作为克利夫兰自然历史博物馆马丁·路德·金发现日的一部分而创建的，该项目展示了天然聚合物是如何日常使用的。聚连环烷和聚轮烷都是由联锁在一起并通过机械键固定在一起的组分组成的。在本研究中，研究了组分的结构如何影响产品的分布、分子量和聚连环烷的性能。此外，研究活动扩大了可通过金属超分子模板方法获得的联锁聚合物的类型，如双线聚[3]轮烷和滑动环凝胶。这种新型互锁聚合物结构，以及对这种体系的更好的结构/性能理解，使材料的开发具有展示不同寻常的性能矩阵的潜力。这些结构为新的聚合物致动器和材料打开了大门。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 Dr. Stuart J. Rowan from University of Chicago to develop synthetic methods to build new polymer architectures and to study how these architectures impact polymer properties. Conventionally, polymers or long chain molecules are prepared from smaller molecules that are joined together by carbon-carbon covalent bonds. Covalent bonding occurs when pairs of electrons are shared by atoms and it constitutes the basic building principle for all of organic chemistry. The approach in this work is rather unique because the repeating units in the targeted polymers are not covalently bonded to one another, yet cannot be separated unless covalent bond breakage occurs. Essentially, the monomer units are interlocked together like individual pieces in a metal chain or necklace. The molecular version of two interlocked rings is called a catenane and, when they are liked together the overall structure is a polycatenane (it looks like a metal chain). A related interlocked polymer in which a long polymer molecule is threaded through a ring molecule, like beads on a string, is called a polyrotaxane. Such interlocked polymeric materials may have unique physical properties and potential applications in the areas of molecular electronics, energy absorbing materials, nanorecording and optical bioimaging. The activities associated with this award increase broadening participation and enable training of high school, undergraduate, and graduate students in synthetic organic chemistry and polymer chemistry. The outreach program 'Natures Materials' is created as a part of the Cleveland Museum of Natural History's Martin Luther King Discover Day which demonstrates how natural polymers are used everyday. Both polycatenanes and polyrotaxanes consist of components that are interlocked together and held in place with a mechanical bond. In this research, an investigation on how the structure of the components can be used to impact product distribution, molecular weight, and the resulting properties of polycatenanes is conducted. In addition, research activities expand the types of interlocked polymers that can be accessed via the metallosupramolecular template approach to doubly-threaded poly[3]rotaxanes and slide ring gels. The access to such new interlocked polymeric structures, along with a better structure/property understanding of such systems, allows the development of materials with the potential to exhibit an unusual property matrix. These structures open the door to new polymeric actuators and materials.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.