Collaborative Research: Electronic and Ionic Transport in Block Copolymers

University Of California-Berkeley, Berkeley CA

Investigators

Abstract

0966632 Balsara Intellectual Merit: This energy related project is a collaborative experimental and theoretical study of the effect of morphology on electron and ion conduction in nanostructured polymer materials with clearly defined independent channels for electronic and ionic transport. Regio regular poly(3-hexylthiophene) block polyethyleneoxide (PHT-PEO) will be synthesized by coupling aldehyde terminated PHT chains with living styryl-PEO anions, and doped with the appropriate salts to make the PHT domain electron conducting and the PEO domain ion-conducting. The morphology of the mixtures and charge carrier distribution will be characterized by standard techniques such as electron microscopy and X-ray scattering, as well as element specific techniques such as energy filtered EM and resonant soft X-ray scattering. A combination of DC- and AC-impedance spectroscopy will be used to measure the ionic and electronic conductance of the doped copolymer. Concurrently with the experimental efforts, theoretical and simulation studies will be performed to understand the underpinnings of the experimental observations regarding morphology and dopant distribution, and to provide insight for designing second generation systems with optimal properties. In particular, a ribbon coil model will be developed to predict the morphology of PHT-PEO systems. Theories that incorporate both ion solvation and chain deformation will be used to predict dopant distribution. Computer simulations used to predict ion transport will be validated using experimental measurements. This work will be the first study of the simultaneous electronic and ionic transport in nanostructured polymer materials. The combined experimental and theoretical efforts will yield rich insights into: how charge carries are distributed in nanostructured materials, how the motion of charge carriers couples to the segmental dynamics of the polymers, how the local nanostructure and large scale grain structure influences charge transport, and how doping agents alter the morphology of the self assembled polymeric structures. These insights may lead to entirely new design strategies for electrode architectures in rechargeable batteries and fuel cells. Broader Impacts: The research is in sync with the nationwide efforts at creating clean and more efficient energy technologies. The systems studied have potential to directly translate into new battery technologies. Furthermore, in both PI's home departments, there is an increasing need among the graduate students to work in energy related research areas; the projects fulfill that need by providing them with the opportunity to do research in a technologically important area, while receiving a multidisciplinary training in theory, simulation, modeling, thermodynamics, synthesis and characterization of polymers, optics, scattering, and electrochemistry. Equally important, the proposed research serves as a platform for developing new educational packages for high school and undergraduate students. In this respect, the PIs will develop and execute lectures and demonstrations on electrochemistry and batteries as part of the Math and Science Summer Academy program at Berkeley.