Conducting Cyclic Polymers

佛罗里达大学的Adam S Veige和Brent S Sumerlin教授在化学系的大分子、超分子和纳米化学（MSN）项目的支持下合成了环状聚合物。大多数塑料是由线性聚合物组成的（由相对较小的分子片段组成的链，称为单体，它们连接在一起）。该项目旨在通过消除聚合物链末端和创造环状聚合物来开发一种新型和改进的塑料。对环状聚合物进行了表征，并与它们的线性类似物进行了性能比较。操纵聚合物的成分和结构以产生所需的一系列性能（如强度、耐热性和导电性）的能力大大扩展了塑料在现代工业经济中的许多作用。与线性聚合物相比，环状聚合物具有显著不同的性质。佛罗里达大学开发的催化剂技术使循环聚合物的高效生产成为可能。一些塑料能够导电，并用于有机发光二极管（oled）。这个项目旨在创造第一个导电的环状聚合物。该项目为学生提供现代无机和有机金属化学的实践训练。在一年一度的Mall化学日活动中，展示了环状聚合物原理的演示，并向公众展示。在这个项目中，佛罗里达大学发现的一种关键催化剂将用于合成大环多烯聚合物。主要目标是：1)在保持其溶解度的同时，最大限度地提高环聚（乙炔-co-1-炔）聚合物的导电性；2)通过取代的聚炔侧链连接迫使聚合物对准，从而提高共轭性；3)合成了一种新的碳同素异形体环聚[n]碳。导电环聚合物是稀缺的，其循环拓扑对电导率的影响尚未被探索。该项目采用了一种钨催化剂，能够将乙炔插入到不断增长的金属循环中。然后通过还原消除终止聚合反应得到环状聚乙炔。乙炔和取代乙炔的共聚产生独立的有光泽的薄膜，在掺杂后被询问电导率。取代乙炔对于制造可溶性聚乙炔是必不可少的；然而，它们掺入到聚合物链中固有地通过扭转聚合物主链而降低了共轭。该项目旨在通过聚合后功能化连接取代基来约束聚合物主链的几何形状，从而生产导电环状聚合物。最后，本项目还旨在合成一种新的碳同素异形体环聚[n]碳。线性聚[n]碳是不稳定的，除非链端被功能化。由于没有链端，预计环状聚合物将更加稳定，因此具有潜在的可分离性。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。

Professors Adam S Veige and Brent S Sumerlin of the University of Florida are supported by the Macromolecular, Supramolecular, and Nanochemistry (MSN) Program of the Division of Chemistry to synthesize cyclic polymers. Most plastics are composed of linear polymers (chains of relatively small molecular fragments known as monomers that are joined together). This project aims to develop a new and improved class of plastics by eliminating the polymer chain ends and creating cyclic polymers. The cyclic polymers are characterized and their properties are compared with their linear analogs. The ability to manipulate the composition and structure of polymers to yield a desired set of properties, such as strength, heat resistance and electrical conductivity, has significantly expanded the many roles plastics play in our modern industrial economy. Cyclic polymers have dramatically different properties compared to their equivalent linear counterparts. Catalyst technology developed at the University of Florida enables the efficient production of cyclic polymers. Some plastics are able to conduct electricity and are used in organic light emitting diodes (OLEDs). This project aims to create the first electrically conducting cyclic polymers. The project provides the students involved with hands-on training in modern inorganic and organometallic chemistry. Demonstrations that illustrate the principles of cyclic polymers are developed and presented to the general public during an annual Chemistry Day at the Mall event. In this project, a key catalyst which was discovered at the University of Florida will be employed for the synthesis of macrocyclic polyene polymers. The main thrusts are: 1) to maximize the conductivity of cyclic poly (acetylene-co-1-alkyne) polymers while retaining their solubility; 2) to improve conjugation by forcing the alignment of the polymer via side-chain ligation of substituted polyalkynes; and 3) to synthesize cyclic poly[n]carbon, which represents a new carbon allotrope. Conducting cyclic polymers are scarce, and the consequence of their cyclic topology on conductivity have yet to be explored. The project employs a tungsten catalyst that is capable of inserting acetylenes into a growing metallacycle. Cyclic polyacetylenes are then obtained by termination of the polymerization reaction via reductive elimination. Copolymerization of acetylene and substituted acetylenes produce free standing lustrous films that are interrogated for electrical conductivity upon doping. Substituted acetylenes are essential for creating soluble polyacetylenes; however, their incorporation into the polymer chain inherently reduces conjugation by twisting the polymer backbone. This project aims to produce conducting cyclic polymers through linking the substituents by post-polymerization functionalization to constrain the geometry of the polymer backbone. Finally, the project also aims to synthesize cyclic poly[n]carbon, which represents a new carbon allotrope. Linear poly[n]carbon is unstable unless the chain ends are functionalized. By having no chain ends it is expected that the cyclic polymer will be more stable and therefore, potentially isolable.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.