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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A novel perfluoropolyether (PFPE) structure terminated on one chain end by a hydroxyl end group and on the other end by a cyclotriphosphazene derivative was studied. The interactions that developed at the interface between molecularly thin films of this material (A20H) and amorphous nitrogenated carbon surfaces were investigated using contact angle goniometry, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and imaging ellipsometry. The results demonstrate that both the cyclotriphosphazene and the hydroxyl end group of monolayer A20H films are capable of attractive interactions with the carbon surface. These interactions induce a layering in the adsorbed film that is manifested in an oscillatory dependence of the surface free energy on applied A20H film thickness. The thickness of the first A20H monolayer is determined from the first minimum in the surface energy to be 13.0 ± 1.0 Å for the 2400 molecular weight material and 15.0 ± 1.0 Å for the 3100 molecular weight material studied. The second A20H monolayer is not completely wetting on the first monolayer. This results in an autophobic dewetting when A20H films in excess of the monolayer thickness are applied to the carbon surface. The mobilities of A20H monolayer films were also qualitatively compared to that of the hydroxyl-terminated PFPE, Fomblin Zdol. While interaction of the cyclotriphosphazene end group with the carbon surface increases the load-bearing capability of the PFPE film when compared to Zdol, it also has the effect of decreasing the mobility of the adsorbed film.

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We have investigated the resistance of a novel end-functionalized perfluoropolyether (PFPE) lubricant film to slider-disk interactions caused by low-flying sliders. The PFPE lubricant is based on the CF 2 CF 2 CF 2 O main chain monomer unit. Both slider-disk interactions and the formation of lubricant moguls are significantly reduced compared to the Fomblin Z backbone, (CF 2 O) p -(CF 2 CF 2 O) q . These results are interpreted on the basis of ab initio quantum chemical computations that show that the barrier to internal rotation about the C-O bond in the CF 2 CF 2 CF 2 O monomer unit is significantly larger than in the CF 2 O monomer unit that is bordered by another CF 2 O monomer unit, *8 kcal/mol compared to \2 kcal/mol, respectively. It is proposed that main chains containing CF 2 O monomer units will be very flexible and hence their physical properties will be more sensitive to adhesive and cohesive interactions, while main chains containing CF 2 CF 2 O and CF 2 CF 2 CF 2 O monomer units will be comparatively stiffer and hence their physical properties will be less sensitive to adhesive and cohesive interactions.