Conducting Cyclic Polymers

佛罗里达大学的亚当·S·维格教授和布伦特·S·苏默林教授得到了化学系大分子、超分子和纳米化学计划的支持，以合成环状聚合物。大多数塑料都是由线性聚合物(由相对较小的分子片段组成的链，称为单体连接在一起)组成的。该项目旨在通过消除聚合物链端和产生环状聚合物来开发一种新的和改进的塑料类别。对环状聚合物进行了表征，并与其线性类似物进行了性能比较。能够操纵聚合物的组成和结构来产生所需的一系列性能，如强度、耐热性和导电性，大大扩大了塑料在现代工业经济中扮演的许多角色。与等效线性聚合物相比，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环状聚合物的生产变得高效。一些塑料能够导电，并用于有机发光二极管(OLED)。该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培训。在购物中心一年一度的化学日活动期间，展示了环状聚合物的原理，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。主要的研究方向是：1)在保持其溶解性的同时最大化环状聚(乙炔-1-乙炔)聚合物的导电性；2)通过取代聚炔的侧链连接强迫聚合物的排列来改善共轭作用；3)合成环状聚[n]碳，这是一种新的碳同素异构体。导电的环状聚合物很少，它们的环状拓扑结构对导电性的影响还有待研究。该项目使用了一种钨催化剂，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。乙炔和取代的乙炔的共聚产生了独立的有光泽的薄膜，在掺杂时需要检测其导电性。取代的乙炔对于产生可溶的聚乙炔是必不可少的；然而，它们进入聚合物链本身就会通过扭曲聚合物主链来减少共轭作用。该项目旨在通过聚合后官能化连接取代基来限制聚合物主链的几何形状，从而制备导电环状聚合物。最后，该项目还旨在合成环状聚[n]碳，这是一种新的碳同素异构体。线型聚[n]碳是不稳定的，除非链末端是官能化的。由于没有链端，预计环状聚合物将更稳定，因此具有潜在的隔离性。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.