Effects of end groups on the spreading characteristics of molecularly thin liquid lubricant films in hard disk drives

Spreading characteristics of novel alkanoleamine-terminated perfluoropolyether (PFPE) films on carbon surfaces were investigated experimentally by using a scanning micro-ellipsometer. It was found that the mobility of the alkanoleamine-terminated PFPE films was lower than that of conventional lubricants that have the same number of OH end groups as that of the alkanoleamine-terminated lubricants. The mobility of ZDPA with a dipropylamine end group (no OH end group) has peculiar characteristics. In other words, its mobility is higher than that of Zdol when the lubricant film thickness exceeds one monolayer. However, it is lower than Zdol when the lubricant film thickness is less than one monolayer. This may be due to unique interaction between the ZDPA amine group and the carbon overcoat