Molecular Dynamics Simulation Insight into Two-Component Solubility Parameters of Graphene and Thermodynamic Compatibility of Graphene and Styrene Butadiene Rubber

The effect of the number of layers, various defects and functional groups on solubility parameter of graphene was studied through molecular dynamics (MD) simulation. We predigested three-component Hansen solubility parameters (δ_D, δ_P, δ_H) to two-component solubility parameters (δ_vdW, δ_ele), and the two-component solubility parameters of graphene functionalized by different groups, such as hydroxyl, carboxyl, amino, methyl and epoxy with different grafting ratios were obtained. Further, the graphene/styrene butadiene rubber (SBR) composites were constructed to investigate the effect of functional groups and grafting ratios on components compatibility. It was found that the defects and functional groups had strong impact on solubility parameter of graphene, whereas the number of layers had a negligible effect. Two-component solubility parameters were proven to be able to predict compatibility of graphene and SBR. Additionally, the common effect of multifunctional groups on solubility parameter was also investigated. The combination of multifunctional groups with a proper content can obtain lower solubility parameter than a single group. The present study is expected to provide significant insight into the relationship between solubility parameter of graphene and compatibility of graphene/SBR composites.