AVS 49th International Symposium
    Surface Science Friday Sessions
       Session SS-FrM

Paper SS-FrM2
Self-assembled Monolayers on Aluminium: The Role of Oxide Surface Chemistry

Friday, November 8, 2002, 8:40 am, Room C-110

Session: Self-Assembly at Surfaces
Presenter: M.R. Alexander, UMIST, UK
Authors: T.A. Lewington, UMIST, UK
I. Liakos, UMIST, UK
G.E. Thompson, UMIST, UK
R.C. Newman, UMIST, UK
E. McAlpine, Alcan International, UK
M.R. Alexander, UMIST, UK
Correspondent: Click to Email
Application of self-assembling organics molecules on oxide-covered, metal surfaces is of growing interest in areas ranging from medical implants@footnote 1@ to adhesion promotion pre-treatments.@footnote 2@ In the latter application area, legislation is driving industry to explore environmentally friendly pre-treatments for aluminium. Corrosion protection has been obtained using di-functional alkyl-phosphonic acids assembled on aluminium as a paint pre-treatment. It has been shown that one of the phosphonic acid head-groups form a phosphonate bond with the hydroxylated oxide film at the surface of the aluminium.@footnote 3@ In addition to coupling of the resin and surface, it has been proposed that hydration is inhibited at the phosphonate-aluminium interface.@footnote 4@ In contrast to the stable gold surface utilised in the assembly of alkane-thiols, the oxide at the aluminium surface is readily hydrated on exposure to ambient conditions.@footnote 5@ It is proposed that this instability causes the inconsistent self-assembly often obtained on the aluminium surface. Thus, the oxide surface chemistry of magnetron sputtered aluminium has been controlled using solution and atmospheric conditioning; the effect on self-assembly of alkane-phosphonic acids is reported. XPS has been used to provide oxide thickness and surface hydroxyl concentration while contact angle and FTIR measurements have been used to probe the SAM coverage and order. Evidence for hydration inhibition by phosphonic acids SAMs is presented. @FootnoteText@ @footnote 1@ G. L. KENAUSIS et al. J Phys Chem B 104 (2000) 3298. @footnote 2@ I. MAEGE et al Prog Org Coatings 34 (1998) 1.@footnote 3@ R. D. RAMSIER et al. Surf Sci 203 (1988) 72.@footnote 4@ A. DAVIS et al. J Mater Sci 20 (1985) 975.@footnote 5@ M. R. ALEXANDER et al. Surf Int Anal 29 (2000) 468.