Electrical Conductivity of Graphene–Polymer\nComposite Foams: A Computational Study

Abstract

We use a combination of the coarse-grained\nmolecular dynamics simulations\nand finite difference method calculations to study electromechanical\ncoupling in composite polymer/graphene foams. In these foams, graphene\nsheets (G-sheets) cover the surface of the foam cells resulting in\na percolating network of graphene sheets. Our simulations have shown\nthat upon uniaxial deformation or under foam swelling conditions,\nthe percolating network of the G-sheets breaks down. This breakdown\nis manifested as an increase of the foamʼs electrical resistance.\nThe disruption of the graphene networks occurs through crack formation\nof the G-shells covering the surfaces of the polymeric foam cells.\nThese cracks are responsible for the hysteresis in electromechanical\nfoam properties observed during loading–unloading cycles. In\nparticular, for uniaxial foam deformations, it requires the application\nof a compressive stress for the foam to retain its initial dimensions.\nComparison between uniaxial and swelling foam deformations shows that\nthere is a stronger variation in the foam resistance under uniaxial\ndeformation conditions.