Synthesis and Characterization of Conjugated Diblock Copolymers (Co-Oligomers)

University Of Chicago, Chicago IL

Investigators

Abstract

This research is aimed at establishing a vigorous project to synthesize various well-defined, conjugated diblock copolymers and to investigate their physical properties. A conjugated diblock copolymer possesses a rod-rod structure and will behave differently than rod-coil types of copolymers. These conjugated diblock copolymers are new architectures of electroactive polymers. The main goal of this work is to understand the kind of electronic and structural properties that the rod-rod types of diblock copolymers will exhibit. To probe these properties, various combinations of conjugated blocks and their synthetic approaches are outlined in this proposal. These combinations vary from having different amphiphilic properties to having different electronic properties. A series of functionalized conjugated oligomers, ranging from oligothiophenes and oligophenylenenvinylenes to oligophenlylenes, will be synthesized. The electronic and physical properties of these oligomers will be investigated as the database for their comparison with diblock copolymers (or co-oligomers). Several of the oligomers obtained will be coupled to form diblock copolymers with various conjugation lengths and electronic properties. Since these block copolymers can undergo phase separation and form self-assembly, microscopic studies of the self-assemblies will be carried out to find the principles underlying their molecular packing and phase behaviors. Copolymers with various redox properties will be coupled to explore electro-optic properties such as optical absorption and luminescence, and photoconductivity and electrical conductivity. Copolymers with an electron-rich block and an electron-deficient one will be functionalized with a hydrophilic side group attached to the first and hydrophobic moiety attached to the latter. These block copolymers will be sued to prepare L-B films, which are very interesting for their molecular-electronic effects due to their built-in molecular "P-N" junction. These block copolymers are expected to undergo phase separations to assemble into nanometer-continuous domains, which will be explored for photovoltaic effect. The investigation of possible applications of the diblock copolymers includes their use in electro-optic devises, such as photovoltaic and electroluminescent devices, molecular-electronic components, and optical switching. Experiments to explore the properties leading to those applications are also proposed.