The Fabrication,Characterization And Tribological Behaviors Biomimetic Nanocomposite Thin Films

Recently, the thin films that mimetic shell or have organic-inorganic orderlyalternating structures were widely investigated. The research results show thatthey have remarkable antiwear and friction reduction behaviors. In this thesis, thelong chain monomers dodecylacrylate, dodecylmethacrylate, the long chaincross-linkers hexanedioldiacrylate and hexanedioldimethacrylate weresynthesized. Both SiO₂/organic and TiO₂/organic nanocomposite thin films thatmimetic shell were fabricated. Their structures were characterized and theirtribological behaviors were studied. The main results and conclusions obtainedare as follows:(1) The structures of the long chain monomers and the long chain cross-linkerssynthesized in our laboratory were characterized by FT-IR, MS, ElementalAnalysis. The results show that the structures of the monomers and thecross-linkers are correct.(2) The SiO₂ nanoparticles whose surfaces were modified by methacryl-oxypropyltrimethoxysilane were fabricated. The surface modified SiO₂nanoparticles, monomers and cross-likers were co-assemblied into organic-inorganic composite thin film on glass substrate through supramolecularself-assembly method. Its structure was characterized using FT-IR, XRD,XPS, SEM. The results show the thin film has organic-inorganic orderlyalternating structure. The interlayer spaces are 3.27nm beforepolymerization and 3.32nm after polymerization, respectively. Theformation mechanism of the thin film was proposed.(3) The tribolgical behaviors of SiO₂/organic layered nanocomposite thin filmthat mimetics shell were studied on still-move friction coefficientinstrument. The friction coefficients of the unpolymerized and polymerizedthin films sliding against Gr15 steel are both 0.1. The friction reductionmechanism can be explained using "brush model" which can effectivelyreduce the shearing strength. The polymerized film has better antiwear lifethan the unpolymerized film because polymerization enhances the strenthof the thin film.(4) The TiO₂ nanoparticles whose surfaces were modified by methacryl-oxypropyltrimethoxysilane were fabricated. The surface modified TiO₂nanoparticles, monomer and cross-likers were co-assemblied intoorganic-inorganic composite thin film on glass substrate throughsupramlecular self-assembly method. Its structure was characterized usingFT-IR, XRD, U-vis and TEM. The results show it has organic-inorganicorderly alternating structure. The interlayer spaces are 4.20nm beforepolymerization and 3.91nm after polymerization, respectively. Itsformation mechanism was proposed.(5) The tribolgical behaviors of TiO₂/organic layered nanocomposite thin filmthat mimetics shell was studied on still-move friction coefficient instrument.The friction coefficients of the unpolymerized and polymerized thin filmssliding against Gr15 steel are both 0.1. The reduce friction mechanism canbe explained using "brush model". The polymerized film has betterantiwear life than the unpolymerized film because polymerization enhancesthe strength of the thin film.