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

Year: 2023

Journal: Applied Surface Science, Volume 615, 2023-04-01, page 156417

Authors: Wang, Yilei; Weng, Can; Deng, Zijian; Sun, Huijie; Jiang, Bingyan

Keywords: Composite mold insert; Demolding; Micro-injection molding; Microfluidic chip; Nanoparticle

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.