Fabrication and performance of nickel-based composite mold inserts for micro-injection molding

[Display omitted] •PTFE, MoS2 and WS2 nanoparticles were uniformly dispersed in composite mold inserts.•The nickel-based composite mold inserts were fabricated by electroforming.•Experiments and simulations showed that the nanoparticles reduced the surface energy.•The optimal friction coefficient would be reduced from 0.75 to 0.25.•Ni-WS2 mold insert solved the demolding deformation of polymer microstructure. During the demolding stage of micro-injection molding (μIM), reducing the interfacial interactions (mainly adhesion and friction forces) between the contact interfaces is the key to achieve non-destructive molding of polymer micro/nano structures. In this study, Ni-based composite mold inserts using polytetrafluoroethylene (PTFE), molybdenum disulfide (MoS2) and tungsten disulfide (WS2) with low surface energy and low friction coefficients were fabricated by electroforming. Different nanoparticles could be uniformly distributed in the composite mold inserts without agglomeration at low concentrations, and the orientation of nickel crystal was found to be unchanged by phase composition analysis. The surface energy and adhesion of the inserts could be effectively reduced after the addition of nanoparticles. The molecular dynamics simulation results showed that the value of water contact angle could be closer to the experimental value by adding a surface roughness factor. Due to the self-lubricating property of nanoparticles, the friction coefficient was reduced from 0.75 for pure Ni to 0.25 for WS2 with a concentration of 0.2 g/L. The use of the composite mold inserts with low surface energy and low friction coefficient would solve the problem of microstructure deformation in the demolding stage of injection molded polymer microfluidic chips.