Conformation and Fundamental Properties of Novel Lubricant TA-30 for Near Contact Magnetic Recording

Abstract

A novel perfluoropolyether (PFPE) lubricant called TA-30 has been developed recently. We investigate the conformation of TA-30 on diamond-like carbon (DLC) thin films, by attempting the direct observation of a lubricant film by atomic force microscopy (AFM) using a fluoride probe. We investigate the fundamental properties of a TA-30 lubricant film, such as its spreading characteristics, and the film thickness dependence of surface energy. Considering these experimental results, we conclude that the conformation of TA-30 is considerably different from that of conventional Z-tetraol2000 whose molecular height is 1.7 nm and which was adsorbed on the DLC surface with the random coil. The TA-30 molecules are adsorbed rigidly to the DLC surface with double layers. The thickness of the first TA-30 layer is *0.9 nm (similar to diameter of the PFPE backbone) and that of the second layer from the DLC surface is 1.4 nm. Since TA-30 has a lower film thickness than Z-tetraol2000 on the DLC surface, it can have two layers, even if the film thickness is approximately of the order of 1 nm, whereas Z-tetraol2000 does not cover the DLC surface and does not form the complete first layer. In addition, we conduct slider touchdown and takeoff hysteresis tests by using TA-30 and Z-tetraol2000. It is confirmed that the use of TA-30 can improve the head-disk interface (HDI) reliability at lowfly-height conditions.

Boundary Lubricant Film Properties versus Molecular Polarity of Perfluoropolyethers Containing a Pendant Chain

“…These aspects are well-understood in terms of the barriers to internal rotation and chain confinement effects due to the pendant branch and are therefore fully anticipated results [3,4]. We also note that the monolayer thickness derived from the terraced flow for TA-30 reported here, ~ 18 Å, is substantially larger than reported by Tagawa et al, ~ 9 Å [11]. A reason for this difference is not yet understood.…”

Single-Chain Conformational Analysis on the Dynamic Main Chain Expansion of a Tethered Perfluoropolyether Boundary Lubricant Film

“…Tagawa et al have recently shown that TA-30 shows more slider-disk clearance than Z-Tetraol at similar film thicknesses [23]. We have also conducted sliderdisk clearance measurements on Z-Tetraol, D-4OH, and TA-30 at the same 11 Å film thickness on identical carbon films (amorphous nitrogenated carbon films).…”

Infrared Spectroscopic Analysis of Sub-Monolayer Perfluoropolyether Films Based on the ^|^mdash;[(CF2)nO]^|^ndash; Monomer Unit for n = 2, 3 and 4

“…For example, removing the -(CF 2 O)-monomer unit in -(CF 2 O) p -(CF 2 CF 2 O) q -is one way in which chain flexibility can be reduced. Consequently, PFPEs derived from -(CF 2 CF 2 O)-, or -(CF 2 CF 2 CF 2 O)-, or -(CF 2 CF 2 CF 2 CF 2 O)monomer units are increasingly being utilized [9,10].…”