Investigation of Friction and Wear Behaviors of Cu(OH)2-doped Polyelectrolyte Multilayers

Molecular deposition technology was used to prepare pristine polyelectrolyte multilayers(PEMs) by sequential adsorption Poly(diallyldimethylammonium chloride)(PDDA) and poly(sodium 4-styrenesulfonate)(PSS) alternately on quartz and Si substrate.The Cu(OH)_2-doped polyelectrolyte multilayers were achieved using a series of cyclical adsorption-hydrolysis processess in which copper ions bind to the sulfonate groups of the pristine PEMs and then hydrolysis in an alkali solution.UV-vis absorption spectroscopy,atomic force microscopy and transmission electron microscopy were used to observe the structure and the morphology of before and after the in-situ synthesis copper hydroxide nanoparticles in the PEMs matrix.Tribological behaviors of the Cu(OH)_2-doped polyelectrolyte multilayers were studied on the LKDM-2000 tribology measurement apparatus,and results show that friction coefficient of the Cu(OH)_2-doped polyelectrolyte multilayers is higher and has no obvious change with increase of normal load compared with pristine PEMs.Cu(OH)_2-doped polyelectrolyte multilayers exhibit higher durability,because the inorganic nanoparticles in the PEMs enhanced load-carrying capacity.The main wear mechanism is adhesive wear,and Cu(OH)_2 nanoparticles in the PEMs mitigated plastic deformation and slowed down adhesive wear owing to their existence.