Simulating the replication and entanglement of semi-rigid polymers in nano-injection moulding

Abstract

Many polymers have been used to design polymer/metal composite structures with high bond strength through nano-moulding technology. However, whether high-molecular-weight polymers flow deeply into nanostructures and whether polymer entanglement hinders complete infiltration remain contentious issues in theoretical studies. In this study, the effects of the injection pressure, molecular weight of the semi-rigid polymer [polyphenylene sulfide (PPS)], and nanostructure size of the metal surface on the replication quality were investigated by molecular dynamics simulations. Increasing the injection pressure and polymer molecular weight increased the replication quality at practical temperatures. PPS with various chain lengths could completely infiltrate the nanopores. The nanostructure size of the metal surface was weakly negatively correlated with the filling rate, but it was substantially negatively correlated with the infiltration behaviour of the entire PPS chain. The reasons for infiltration of long-chain PPS and the steady evolution of the entanglement density were investigated. The steady entanglement density of PPS indicates that entanglement is not the main reason for the low filling rate. From the mobility of a single chain, the PPS chain flows into nanopores in a snake-like fashion. These results provide new insights to improve the adhesion strength between polymers and metals in nano-injection moulding.