Self-assembled monolayer formation on magnetic hard disk surface and friction measurements

Abstract

Self-assembled monolayers (SAMs) of 1H,1H,2H,2H-perfluorodecyltriethoxysilane were deposited on the magnetic hard disk surface by immersion. SAM formation was confirmed by contact angle measurement, ellipsometry, and x-ray photoelectron spectroscopy. Friction of unlubricated, SAM-coated, and perfluoropolyether (PFPE) Zdol-coated disk surfaces was measured with lateral force microscopy, spin-stand tester, and scratch tester. The SAM-coated disk surfaces had lower friction as compared to the unlubricated disk surfaces. This result is in agreement with the hydrophobic nature of the SAM-coated surface. On the other hand, friction of the SAM-coated surface was larger than the 2-nm-thick PFPE-coated surface, even though the hydrophobicity of the SAM-coated surface was higher than that of the PFPE-coated surface. This would be attributed to the mobility of the multilayered PFPE lubricant, whereas the friction of SAM-coated surface was comparable or even better when compared to that of 1.1-nm-thick PFPE-coated surface, which had a small mobile portion.