Conjugated Polymer Networks

Case Western Reserve University, Cleveland OH

Investigators

Abstract

It is expected that the introduction of conjugated cross-links between conjugated macromolecules can lead to macromolecular networks with most interesting optic and electronic characteristics. However, the knowledge base regarding the synthesis and processing of well-defined materials with this structural motif is very limited. Thus, a research program is proposed, which is focused on the design, synthesis and exploration of well-defined conjugated polymer networks. The proposed research addresses the synthesis and investigation of different classes of polymeric materials, including poly(p-phenylene ethynylene) (PPE_ and poly(thiophene) (PT) deriavatives, and various fields of potential applications. The envisioned activities will be focused on organometallic hybrid materials in which metal-ligand interactions between the conjugated macromolecules and metals allow the controlled formation of conjugated cross-links. This general framework is particularly attractive, since it readily permits synthetic access to the desired target materials through ligand-exchange reactions and also allows for adequated processing schemes. On the one hand, it is intended to directly utilize functionalities that are integral part of the polymer backbones as binding sites, such as the ethynylene moieties comprised in the PPE. The latter form stable complexes with a variety of metal centers, including Pt(0) and Pt(0), which will form the conjugated cross-links. On the other hand, it is envisioned to also integrate specific ligand sites into the conjugated polymer. Bipyridine moieties, which are readily integrated into the polymers under consideration and from stable complexes with a variety of metal centers, represent an illustrative example. Initially focusing on charge-transport characteristics, electrical conductivity and nonlinear optic response, it is planned to systematically investigate the influence which the cross-links exert on the electronic and photophysical properties of the novel materials. The research in this proposal contributes new and original ideas to the current international effort in the fields of chemistry, materials science, and physics of conjugated polymers. It is anticipated that it will provide firm answers to the fundamental questions how conjugated cross-links can be conveniently introduced into these materials without compromising their processability, and how this structural motif can be employed to influence the material's optic and electronic characteristics in a beneficial way. Because of the exemplary and fundamental character, the research is expected to provide a broad intellectual basis for the future design, synthesis and application of functional materials with unusual and unique optic and electronic properties. With the aim to develop innovative and stimulating curricula at undergraduate and graduate level and in an attempt to integrate research and education, the proposed research is complemented with a number of educational elements. The latter are intimately related to the research activities of the PI and include the creation of undergraduate research opportunities, the development of a new cutting-edge course on photo- and electrofunctional polymers, and the development of a pioneering outreach program - the 'Polymer Science Days' - which is implemented in collaboration with the Cleveland Museum of Natural History. The proposed initiatives complement 'routine' teaching assignments and address the development of innovative and stimulating curricula.