Graphene is a two-dimensional material with a hexagonal array of sp<sup>2</sup> hybridized carbon atoms. It is known for its excellent electrical, mechanical, and thermal properties. Potential applications of graphene include supercapacitors, composites, biosensors, ultra-thin touchscreens, and solar cells. However, utilizing these extraordinary properties often requires exfoliating graphite into individual graphene sheets. Our group has found that graphite exfoliates at the high energy interface of water and oil in order to minimize the free energy of the system. This thermodynamically driven process results in water-in-oil emulsions. With this approach, we have made conductive foams by polymerizing the continuous phase of graphene stabilized water-in-oil emulsions. These foams are conductive due to the thin film of overlapping graphene sheets lining the cells of the foams providing a self-assembled percolating network of graphene. To directly study the conductivity of the graphene films embedded in these foams, we recreate the water-graphene-polymer films at a flat interface and directly measure the surface resistance. The presence of a crosslinker in the polymer phase is shown to be critical for these films to be conductive. The sheet resistance values are also sensitive to the type of monomer used for polymerization. We studied the effect of crosslinker type and concentration, initiator concentration, aqueous phase salt concentration, and inhibitor, on exfoliation and electrical conductivity of the graphene films. In addition, Raman spectroscopy, optical microscopy, SEM, and other techniques were used to study these interfacial graphene films.

Understanding the electrical conductivity of overlapping graphene films at polymer/water interfaces

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.