Fabrication and tribological properties of self-assembled monolayer of n-alkyltrimethoxysilane on silicon: Effect of SAM alkyl chain length

作者：Huo, Lixia; Du, Pengcheng; Zhou, Hui; Zhang, Kaifeng; Liu, Peng^*

来源：Applied Surface Science, 2017, 396: 865-869.

DOI：10.1016/j.apsusc.2016.11.049

• Self-assembled monolayer (SAM)
• n-alkyltrimethoxysilane
• Alkyl chain length
• Tribological behavior
• Silicon wafer

It is well known that the self-assembled organic molecules on a solid surface exhibit the friction-reducing performance. However, the effect of the molecular size of the self-assembled organic molecules has not been established. In the present work, self-assembled monolayers (SAMs) of n-alkyltrimethoxysilanes with different alkyl chain lengths (C-6, C-12, or C-18) were fabricated on silicon substrate. The water contact angles of the SAMs increased from 26.8 degrees of the hydroxylated silicon substrate to near 60 degrees after self-assembly. The atomic force microscopy (AFM) analysis results showed that the mean roughness (R-a) of the SAMs decreased with increasing the alkyl chain length. The tribological properties of the SAMs sliding against Al2O3 ball were evaluated on an UMT-2 tribometer, and the worn surfaces of the samples were analyzed by means of Nano Scratch Tester and surface profilometry. It was found that lowest friction coefficient and smallest width of wear were achieved with the SAMs of C-12 alkyl chain (C-12-SAM). The superior friction reduction and wear resistance of the SAMs in comparison with the bare silicon substrate are attributed to good adhesion of the self-assembled films to the substrate, especially the C-12-SAM with desirable alkyl chain length.

• 出版日期2017-2-28
• 单位兰州大学; 兰州空间技术物理研究所