Self-assembled monolayer of multiply-alkylated cyclopentenes on silicon via thiol-ene "click" reaction and its self-lubricating properties

Self-assembled monolayer (SAM) of multiply-alkylated cyclopentenes (MACEs), homologue of the famous hydrocarbon mobile lubricant multiply alkylated cyclopentanes (MACs), was fabricated as self-lubricating film on the surface of the thiol-functionalized silicon wafer (HS-Si) via facile thiol-ene "click" reaction, induced with UV-light or heating. The surface property analysis, including static contact angle and surface roughness, indicated the successful self-assembly. The microtribological tests of the different samples on a UMT-1 tribometer (CETR) in a ball-on-plate contact configuration showed that the SAMs possessed excellent self-lubricating property, in which the SAM_H obtained via the heating-induced thiol-ene "click" reaction had the lower friction coefficient and longer tribological durability than the SAM_UV one prepared under UV-irradiation. The proposed self-lubricating strategy is expected to be used in the lubrication of micro-/nano-electromechanical systems (MEMSs/NEMSs).