A molecular simulation study on the adhesion behavior of a functionalized polyethylene-functionalized graphene interface

Molecular dynamics simulations were applied to investigate interfacial adhesion between functionalized polyethylene (fPE) and functionalized graphene (fG) surfaces. In order to functionalize the PE and graphene surfaces, various types of functional groups were covalently bonded on the surfaces in a random manner. Adhesion between fPE and fG surfaces was evaluated by the calculation of work of separation (W_sep), while the interfaces were not allowed to relax. According to the simulation results, the combination of the atomic roughness effect and the electronic properties of the functional groups had influence on the adhesion between PE and graphene. The effect of surface reorganization was also investigated by devoting sufficient time for relaxation of the interface. The adhesion in the relaxed interfaces was evaluated via the work of adhesion (W_adh). Relaxation of the interface caused to decrease the atomic roughness of the PE surface, which enhanced adhesion in all of the systems compared to their unrelaxed models. In addition to surface flattening, relaxation also brought about an increase in the atomic density at the interface, which led to enhance the van der Waals interaction and increase interfacial adhesion.