Guided Design of Composite Graphene-Polymer Foams: From Graphene Stabilized Emulsion to Electrically Conductive Foams*

The surface activity of graphene enabled synthesis of composite polymer/graphene foams showing a strong coupling between electrical and mechanical foam properties. To develop a general framework for computationally driven design of composite polymer/graphene foams we use large scale coarse-grained molecular dynamics simulations. In particular, we study the affinity of the 2D elastic graphene-like sheets (G-sheets) to the interface between two immiscible solvents. The established envelop of interaction parameters was used to model emulsion polymerization resulting in polymeric foams which cells are coated with elastic G-sheets (G-shells). Upon uniaxial deformation or under foam swelling conditions, the percolating network of the G-sheets coating foam cells breaks down. This break down is manifested as an increase of the foam's electrical resistance. The disruption of the graphene networks occurs through crack formation of the G-shells covering the surfaces of the polymeric foam cells. The results of the computer simulations are compared with corresponding experimental studies of the graphene stabilized emulsions and of mechanical and electrical properties of composite graphene/polymer foams.