The tribological behavior of spin-assisted layer-by-layer assembled Cu nanoparticles-doped hydrophobic polyelectrolyte multilayers modified with fluoroalkylsilane

Abstract

Abstract Hydrophobic polyelectrolyte multilayers (PEMs) doped with Cu nanoparticles and modified with fluoroalkylsilane were prepared by a series of reaction cycles which consist of cycling the PEMs-coated substrate in Cu 2+ and NaBH 4 solutions, where the polyelectrolyte multilayers were constructed by alternate pipetting of the solutions of poly(diallyldimethylammonium chloride) and poly(sodium 4-styrene sulfonate) onto a spinning substrate. The as-prepared hydrophobic surfaces were characterized by means of X-ray photoelectron spectroscopy, atomic force microscopy, and contact angle measurement. The micro-friction and macro-tribological behavior of the multilayers were investigated. Results indicate that the micro-tribological behavior of the PEMs obeys the modified Amonton's Law, and the macro-tribological behavior of the Cu nanoparticles-doped hydrophobic PEMs is closely related to the wettability. Namely, the more hydrophobic the surfaces are, the longer the antiwear life is. Furthermore, the hydrophobic surfaces have lower friction coefficient under water lubrication than under dry-sliding. The reason lies in that the hydrophobic PEMs have low surface energy and less energy loss during sliding under water lubrication, leading to a lower friction coefficient.