Chemical Properties of a Perfluoropolyether Lubricant with Functional Groups of Pentafluorobenzyl on Hard Disk Media

Abstract

A perfluoropolyether lubricant (LUB-B) with pentafluorobenzyl functional groups at both ends of the main chain was synthesized by the authors, and the chemical characteristics of its film of 2.0±0.2 nm thickness on hard disk media were investigated by time-of-flight secondary ion mass spectrometry and compared with those of a synthesized lubricant (LUB-A) with benzyl groups and the commercial AM3001 lubricant with (3,4-dioxomethylenephenyl)methyl groups. AM3001 lost 94% of its functional groups from the main chain on the disk surface after a 672-h exposure even in a regular clean room at 23°C and 55%RH. LUB-A lost 35% of its functional groups after a 768-h exposure. LUB-B hardly lost any of its functional groups even after a 768-h exposure, and showed the highest chemical stability. It was suggested that hydrolysis at the ether linkage between the main chain and the functional group eliminated the functional groups from the main chain. The decomposition rate seemed to depend on the chemical stability of the benzyl cation.