Preparation and micro-tribological property of hydrophilic self-assembled monolayer on single crystal silicon surface

A kind of nano-film was prepared by self-assembling 6-(3-triethoxysilylpropylamino)-1,3,5-triazine-2,4-dithiol monosodium (TES) on the surface of single crystal silicon with hydroxylated pretreatment. The features of the self-assembled monolayer (SAM) were characterized by contact angle meter, spectroscopic ellipsometer, atomic force microscope, X-ray photoelectron spectroscopy and infrared spectroscopy. The experimental results show that the contact angle of distilled water for self-assembled monolayer (SAM) was 35.5° and the film thickness was 3.7 nm, and orderly directional nano-clusters were covered on the surface by observation of the topography. Besides, the friction and wear properties of the SAM were investigated under micro-load by universal micro-tribotester. Compared with the substrate, the friction coefficient of the SAM was effectively reduced from 0.494 to 0.102, which was due to the lubricant of the SAM coating. Meanwhile, the film was not destroyed until 130 cycle times of reciprocating gliding under load of 10 g. The friction and wear tests show this hydrophilic SAM also has a lubrication effect on the surface while other SAMs often exhibited hydrophobic properties. It is expected that the hydrophilic SAM will be applied in micro electromechanical systems as the solid lubricant coatings.