Fulvenyl-Functionalized Polyisocyanides: Redox-active (Cross-) Conjugated Polymers as Materials for Organic Polymer Batteries and Electrochromic Diodes

该研究项目旨在结合富尔烯和多异氰酸酯（PICs）的特性，以获得一种新型的可逆氧化还原活性共轭聚合物，该聚合物可作为有机聚合物电池中的电荷存储材料，或作为电致变色二极管中的氧化还原活性染料。多异氰酸酯是一种由sp2杂化碳原子为主链组成的共轭聚合物。然而，聚合物的电子结构是这样的，主链内的碳原子由单键连接，因此是交叉共轭的。因此，没有观察到与扩展共轭相关的典型电子效应。然而，在共轭侧链中引入具有氧化还原活性的氟乙烯基，使得聚合物中的电化学还原或氧化可能促进pi-电子沿着聚合物主链重新分布，将其转化为完全共轭的聚乙炔类pi-体系。理想情况下，这种氧化还原反应将允许电化学可逆地切换聚合物的颜色，例如，从几乎无色到黑色。此外，引入特定的氧化还原活性位点允许聚合物在每个重复单元中存储多达一(1)个满电荷。对于最简单的系统，这相当于能量密度高达200-300 Ah/kg，与传统的铅/硫酸电池（177 Ah/kg）相比具有优势。资金将主要用于制备新的三、五、七氟乙烯基功能化聚苯乙烯及其物理、光学和电化学表征。有机电子器件的制备将与独立资助的合作伙伴密切合作。

The research project is aimed at combining the properties of fulvenes and polyisocyanides (PICs), in order to access a new type of reversibly redox-active conjugated polymer that may serve as charge storage material in organic polymer batteries, or as redox-active dye in electrochromic diodes. Polyisocyanides are formally conjugated polymers that consist of a backbone of sp2-hybridized carbon atoms. However, the electronic structure of the polymer is such that the carbon atoms within the main-chain are linked by single bonds and are therefore cross-conjugated. As a consequence, electronic effects typically associated with extended conjugation are not observed. However, introduction of redox-active fulvenyl-groups into conjugated side-chains furnishes a polymer in which electrochemical reduction or oxidation may facilitate to a redistribution of the pi-electrons along polymer-backbone, transforming it into a fully conjugated polyacetylene-like pi-system. Ideally, this redox-response will allow to reversibly switch the color of the polymer electro-chemically, e.g. from virtually colorless to black. Furthermore, the introduction of specific redox-active sites allows the polymer to store up to one (1) full charge per repeat unit. For the simplest conceivable systems this corresponds to energy densities of up to 200-300 Ah/kg, which compares favorably e.g. with the classic lead/sulfuric acid battery (177 Ah/kg). Funding will be invested primarily in the preparation of new tria-, penta-, and hepta-fulvenyl functionalized PICs, and their physical, optical, and electrochemical characterization. Preparation of organic electronic devices will be pursued in close collaboration with independently funded cooperation partners.