One-pot synthesis and self-assembly of anti-wear octadecyltrichlorosilane/silica nanoparticles composite films on silicon

In order to improve the service life of Si devices applied in micro-electro-mechanical systems (MEMS), anti-wear octadecyltrichlorosilane/silica nanoparticles (OTS/SiO2) composite films were prepared on silicon by sol-gel and self-assembly techniques. The structure, morphology, chemical composition, wettability, anti-adhesion and tribological properties of the films were characterized. The prepared OTS/SiO2 composite films were hydrophobic with water contact angle of 119.0 +/- 0.5 degrees and textured by OTS modified SiO2 nanoparticles with long chain structures. Compared with Si substrate and OTS self-assembled monolayer (SAM), OTS/SiO2 composite films could not only reduce adhesive force to 17.7 +/- 0.5 nN but also reduce friction coefficient to 0.18 +/- 0.02 under a load of 1 N. The anti-wear lifetime was prolonged to 40,897 s, while OTS SAM was gradually worn out in 104 s under the same friction conditions. The synergistic effect of the transferring of OTS SAM as lubrication films and the repairing of abrasive areas by SiO2 nanoparticles accounted for the preeminent wear resistance. OTS/SiO2 composite films are expected to be effectively used in MEMS as high-performance lubrication films.