Effect of polydopamine surface modification on the adhesive properties of nano‐injection molded metal‐polymer interfaces: A molecular dynamics simulation study

Abstract Nano‐injection molding technology is an important method for large‐scale production of metal‐polymer composites of various shapes. The mechanical properties of these materials are closely related to the interfacial process. In this work, polyphenylene sulfide (PPS) and copper (Cu) were selected as candidate polymer and metal materials, and constructed four different polydopamine (PDA) coatings, including monomer, dimer, linear tetramer, and cyclic tetramer, to modify metal surfaces. The molecular dynamics simulations were launched to investigate the interaction behavior of heterogeneous interfaces during nano‐injection molding and the mechanism by which polydopamine affects the adhesion behavior at the copper‐polyphenylene sulfide interface. Results showed that the addition of polydopamine caused the polymer chains to form many anchor points on the contact surface, which inhibited the wall‐slip behavior of the polymer and led to a mushroom‐like movement of the polymer on the wall surface. The interfacial energy, filling rate data revealed that polydopamine contributes to the enhancement of interfacial adhesion properties, and the polydopamine dimer structure is the most effective of the four configurations. The enhancement of interfacial adhesion mainly originates from the enhancement of non‐bonding interactions and entanglement anchoring between PPS‐PDA. Highlights Polydopamine coating inhibits polymer slip behavior in nano‐injection molding. Polydopamine enhances bond strength of metal‐polymer composites effectively. Dopamine dimers have better adhesion properties than other structural dopamine. Polydopamine coating alters the adhesion mechanism at heterogeneous interfaces. The interface failure mode was closely related to the stress loading mode.