title: Comparative Adsorption of Saturated and Unsaturated Fatty Acids at the Iron Oxide/Oil Interface.
abstract: A detailed comparison of the adsorption behavior of long straight chain saturated and unsaturated fatty acids at the iron oxide/oil interface has been considered using a combination of surface study techniques. Both depletion isotherms and polarized neutron reflectometry (PNR) show that the extent of adsorption decreases as the number of double bonds in the alkyl chains increases. Sum frequency generation spectroscopic measurements demonstrate that there is also an increase in chain disorder within the adsorbed layer as the unsaturation increases. However, for the unsaturated analogues, a decrease in peak intensity is seen for the double bond peak upon heating, which is thought to arise from isomerization in the surface-bound layer. The PNR study of oleic acid adsorption indicates chemisorbed monolayer adsorption, with a further diffuse reversible adsorbed layer formed at higher concentrations.
authors.affiliation: Department of Chemistry and BP Institute, Cambridge University , Cambridge, CB2 1EW, United Kingdom.
authors.forename: Mary H
authors.initials: MH
authors.lastname: Wood
authors.affiliation: Department of Chemistry and BP Institute, Cambridge University , Cambridge, CB2 1EW, United Kingdom.
authors.forename: M T
authors.initials: MT
authors.lastname: Casford
authors.affiliation: Helmholtz-Zentrum Berlin für Materialien und Energie , Hahn-Meitner-Platz 1, Berlin 14109, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Steitz
authors.affiliation: School of Biological and Chemical Science, Queen Mary, University of London , Joseph Priestly Building, Mile End Road, London WC1E 7HU, United Kingdom.
authors.forename: A
authors.initials: A
authors.lastname: Zarbakhsh
authors.affiliation: Department of Chemistry and BP Institute, Cambridge University , Cambridge, CB2 1EW, United Kingdom.
authors.forename: R J L
authors.initials: RJ
authors.lastname: Welbourn
authors.affiliation: Department of Chemistry and BP Institute, Cambridge University , Cambridge, CB2 1EW, United Kingdom.
authors.forename: Stuart M
authors.initials: SM
authors.lastname: Clarke
mesh_terms: D000327:Adsorption; D000473:Alkanes / Q000737:chemistry*; D005290:Ferric Compounds / Q000737:chemistry*; D007700:Kinetics; D019787:Linoleic Acid / Q000737:chemistry*; D019301:Oleic Acid / Q000737:chemistry*; D013229:Stearic Acids / Q000737:chemistry*; D013499:Surface Properties; D013816:Thermodynamics
chemical_list: D000473:Alkanes; D005290:Ferric Compounds; D013229:Stearic Acids; C007548:n-dodecane; C000499:ferric oxide; D019301:Oleic Acid; C031183:stearic acid; D019787:Linoleic Acid