A Survey on High Performance Lubricants for Continuous-Magnetic Recording Media in Application of Functional Inorganic Polymers

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In order to obtain high performance-lubricant materials for continuous magnetic recording media, new types of polyorganophosphazene copolymers have been synthesized and characterized materially. These polyorganophosphazenes contain both anchor substituents and lubricant functional groups attached to the phosphorous atoms in backbone chains. One of the copolymer series examined is poly[(p-methylphenoxy)(trifluoroethoxy)phosphazene] (F-P series); the other is poly[(3,4-dimethylphenoxy)(trifluoroethoxy)phosphazene] (F-dM series). These copolymers were obtained via solution polymerization of hexachlorocyclotriphosphazene. Elemental analysis and GPC measurements for these copolymers were carried out to characterize these materials.Completely-amorphous copolymers are necessary for the lubricant designed here. The polyorganophosphazenes were limitedly found to be amorphous in the chemical composition of ca. 50 mol% p-methylphenoxy substituent; their crystal/mesophase transitions almost disapp … More ered in the copolymer composition of 50 mole% of trifluoroethoxy residures. This situation is quite similar in both the F-P and F-dM cases.Grass transition temperatures, Tg's, of the copolymers were determined by a DSC equipment. The Tg's obtaied showed to change linerly as a function of trifluoroethoxy content; this feature was exactly expressed by the Gordon-Taylor equation.The copolymers obtained were disolved in THF solvent, and coated on metal Si substrates using a spin coater. The thickness of the thin layer was to be ca. 0.5 mum. The contact angles of various solvents against the copolymer thin films were measured by a contangle meter. Hydrophobicity of the thin layer increased with an increase in trifluoroethoxy contents. This suggests that lubricity of the copolymer depends strongly on the functional groups introduced to polyphosphazenene. The F-P series was more effective in hydrobobicity than the F-dM series.Occasionally we have determined the exact lattice constants of poly[bis(p-methylphenoxy)- phosphazene] and poly[bis(3,4-dimethylphenoxy)phosphazene] homopolymers. These results helped to consider the chain coformations within the adsorbed-polymer layer on the metal substrate.More works associated with frictional properties for the thin layer will be necessary in the future. Detailed examination for chain conformation in the layer is now in progress. Less