Nanotribological behaviors of in situ nanoparticles doped molecular deposition films

The molecular deposition films of poly （diallyl dimethylammonium chloride） （PDDA） and poly （acrylicacid） （PAA） with Cu2＋ on quartz and glass substrates were prepared in laboratory first, then different bilayers films were dipped into fresh Na2S aqueous solution. As a result, CuS nanoparticles were fabricated in multilayer molecular deposition films in situ. The structure and nanotribological properties of the composite films were analyzed by ultraviolet-visible （UV-visible） spectroscopy, XPS and atomic force microscope （AFM）. It was found that the CuS nanoparticles were homogeneously distributed throughout the whole film. And these films had a much smaller friction force than their substrates and higher antiwear life than pristine PDDA/PAA molecular deposition films. The fluctuation and variation trend of the topography, hardness, and friction with the AFM indentation length were also investigated.