(140c) Microstructural and Transport Properties of Graphene Polyacetylene Mixed Electron-Ion Conducting Films

Polymer nanocomposites based on graphene are promising materials for energy applications because of their electrical and thermal conductivities, processing ease, relatively low cost, and other special characteristics of graphene, such as relatively low mass density and large surface area. Their use as electrodes in electrochemical devices such as lithium-ion batteries requires ionic conductivity, in addition to electronic conductivity. We are interested in composites of conjugated polymers and ionic liquids with graphene nanoplatelets that exhibit both electronic and ionic conductivity. Such dual-conductive polyacetylene films were synthesized through thermal dehydration of poly(vinyl alcohol) precursor films using hydroiodic acid as a catalyst,¹ and incorporating an ionic liquid and graphene in the precursor film. The resultant films were flexible solids, had good thermal stability, and exhibited dual-conductivity that increased with temperature. Because of its electronic conductivity, graphene increased the electronic conductivity of the films beyond that of the conjugated polymer. The incorporation of graphene nanoplatelets in the films also increased the ionic conductivity, even though the complex viscosity of the films (measured using dynamic mechanical analysis) increased significantly. In order to understand this interesting behavior in detail, the microstructure and transport properties were further investigated through molecular dynamics simulations using previously reported procedures,² which provided insights into the unexpected increase in the ionic conductivity with an increase in the complex viscosity of the three-component films. The results of this study will be discussed in the presentation.

References

1. Sreeram, A.; Krishnan, S.; DeLuca, S. J.; Abidnejad, A.; Turk, M. C.; Roy, D.; Honarvarfard, E.; Goulet, P. J. G., Simultaneous Electronic and Ionic Conduction in Ionic Liquid Imbibed Polyacetylene-Like Conjugated Polymer Films. RSC Advances 2015, 5 (107), 88425-88435.

2. Venkatanarayanan, R. I.; Lebga-Nebane, J. L.; Wu, L.; Krishnan, S., Lithium Coordination and Diffusion Coefficients of Pegylated Ionic Liquid and Lithium Salt Blends: A Molecular Dynamics Simulation Study. Journal of Molecular Liquids 2021, 331, 115694.