Surface and Mechanical Characteristics of Alkanethiol Self-Assembled Monolayers

The surface and nanomechanical characteristics of alkanethiol self-assembled monolayers (SAMs) chemisorbed on a gold surface are investigated. The characteristic mechanisms include the surface characteristics, the contact angle, the nanoindentation load, the nanoscratched load, and the scratched speed. Experimental results show that the average surface roughness increased slightly with increasing SAM growth time. The contact surface of the SAMs was hydrophobic phenomenon and exhibit higher contact angles. The indentation depth increased with increasing the growing time of SAM. The load-unload curve showed a hysteresis loop, indicating that the SAM surface has elastic energy dissipation during indentation process. The wear depth increased with increasing scratching load. A decrease in the scratched depth with increasing scratched speed was observed. The damage broadening after scratching at the low speed scratching was larger than at the high speed scratching. The scratched speed dependence was explained that the resistance force in the scratched region increased as the scratching speed was increased.