AVS 47th International Symposium
    Surface Science Friday Sessions
       Session SS+MC-FrM

Paper SS+MC-FrM8
Characterization of Bound Ultrathin Perfluoropolyether-Functionalized Polysiloxane Films on Silicon Oxide Surfaces

Friday, October 6, 2000, 10:40 am, Room 209

Session: Characterization of Oxides and Thin Films
Presenter: F. Parsapour, Colorado State University
Authors: F. Parsapour, Colorado State University
D.G. Castner, University of Washington
D.W. Grainger, Colorado State University
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Current technological demands for magnetic recording media lubrication include a reduction in the head-disk gap, elimination of stiction, and fabrication of a low adhesion protective surface which can withstand thermal and mechanical stresses associated with hard disk drive operation. Perfluoropolyethers (PFPE) are the most commonly used lubricants in the magnetic recording media. These polymers are typically applied thin films to the hard drive overcoat to which they are generally physisorbed. As a result, they are subject to thermal degradation and "spin-off", ultimately resulting in tribological failure modes. Direct attachment of PFPE films is potentially interesting as a foundation for improved friction and wear performance. We have previously reported fabrication of ultrathin films of polysiloxanes functionalized with perfluoropolyether side chains chemisorbed to surfaces and exhibiting structural anisotropy due to separation of various polymer-grafted components normal to the interface. We now report analogous polymer monolayers but with the important chemical and functional distinction of surface bonding to silicon oxide through alkylsilane anchoring groups. These copolymers were synthesized in a single step through the respective PFPE functional and alkylsilane anchor group coupling reactions. Monolayer films were formed on silicon oxide surfaces through the dip-coating method, resulting in hydrophobic immobilized films ~3 nm thick. XPS measurements support a stratified three-layer film chemistry within the monolayer, and an outer interface enriched with the PFPE moiety. AFM experiments show a high degree of coverage of the oxide surface by the copolymer film, and a relatively uniform surface. LFM measurements exhibit low frictional forces in the areas covered by the monolayer film. Force-displacement curves obtained in a fluid environment reveal a low adhesion surface compared to films prepared from copolymers without the PFPE functional group.