Spreading characteristics of novel cyclotriphosphazine-terminated Perfluoropolyether (PFPE) films on carbon surfaces were investigated experimentally by using a scanning micro-ellipsometer. The apparent diffusion coefficients of novel lubricants were also studied in order to evaluate the spreading speed and they were compared with the conventional Zdol. It was found that the mobility of cyclotriphosphazine-terminated PFPE films is lower than that of Zdol. This characteristics is dependent on the interactions between the end groups of the lubricants and carbon surfaces and it is found that the tendency of “work of adhesion” for the lubricants has a good correlation with the mobility tendency of the lubricants. In addition, the monolayer film thickness of novel lubricant films as well as conventional Zdol was identified, which was extracted using Matano interface method. As a result, the existing conformation of novel cyclotriphosphazine-terminated PFPE film on carbon surfaces could be estimated, based on the monolayer film thickness results.

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The spreading characteristics of novel alkanolamine-terminated perfluoropolyether (PFPE) films on carbon surfaces were investigated experimentally by using a scanning micro-ellipsometer. The apparent diffusion coefficients of the novel lubricants were studied in order to evaluate the spreading speed and they were compared with the conventional Z-dol, Z-tetraol, and A20H lubricants. It was found that the mobility of a lubricant is lower when the number of OH end groups is higher. It was also found that the mobility of the alkanolamine-terminated PFPE films was lower than that of conventional lubricants with the same number of OH end groups as that of the alkanolamine-terminated lubricants and that the mobility tendency of the lubricants has a good correlation with their viscosity tendency. In addition, the mobility of ZDPA with a dipropylamine end group (no OH end group) has peculiar characteristics. Its mobility is higher than that of Z-dol when the film thickness of the lubricant exceeds that of one monolayer. However, it is lower than that of Z-dol when the film thickness of the lubricant is less than that of one monolayer. This may be due to the unique interaction between the ZDPA amine group and the carbon overcoat.

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In this study, the effect of temperature on the spreading characteristics of ultra-thin liquid lubricant films in hard disk drives (HDD) was investigated by using three types of lubricants, namely, Zdol2000, Ztetraol2000, and A20H2000. The apparent diffusion coefficient of individual lubricants was evaluated and compared by varying the temperature of disk substrates. As a result, it was found that the mobility of each lubricant increases with the temperature. However, the rate of mobility increase is different for each lubricant, depending on the lubricant material. Furthermore, there exists no quantitative correlation between the mobility increase for ultra-thin liquid lubricant films and the viscosity decrease in bulk lubricant materials due to a rise in the temperature. It was also found that among the test lubricants, A20H2000 has the highest robustness for temperature change. In addition, it could be observed that the evaporation of the mobile fraction of lubricants occurred remarkably over a temperature range of 50– 80 °C.