Effect of multiply-alkylated cyclopentane (MAC) on durability and load-carrying capacity of self-assembled monolayers on silicon wafer

A novel hydrocarbon mobile lubricant, multiply-alkylated cyclopentane (MAC), was deposited on two kinds of self-assembled monolayers (SAMs), i.e. 1H,1H,2H,2H-perfluorodecyltrichlorosilane self-assembled monolayer (FDTS-SAM) and decyltrichlorosilane self-assembled monolayer (DTS-SAM) to form two double-layer films by spinning coating method. The double-layer films, which are called as MAC-FDTS and MAC-DTS, respectively, consist of a strongly bonded phase lubricant (self-assembled monolayer) and a non-bonded mobile lubricant (multiply-alkylated cyclopentane). Friction behavior of FDTS-SAM, DTS-SAM, MAC-FDTS, MAC-DTS on silicon wafers was evaluated using a pin-on-plate test rig. Both FDTS-SAM and DTS-SAM markedly decreased the friction coefficient of Si substrate. However, they played the role of friction-reducing and anti-wear only at low loads of 50 and 100 mN, respectively. In contrast, when MAC deposited on the two kinds of SAMs, it could markedly reduce the friction coefficient of DTS-SAM and significantly enhance their durability and carrying-load capacity from 50 and 100 mN to 150 and 200 mN, respectively.