title: Unsaturated fatty acids in alkane solution: adsorption to steel surfaces.
abstract: The adsorption of the unsaturated fatty acids oleic, linoleic, and linolenic acid on steel surfaces has been investigated by means of a quartz crystal microbalance (QCM). Two different solvents were used, n-hexadecane and its highly branched isomer, viz., 2,2,4,4,6,8,8-heptamethylnonane. The area occupied per molecule of oleic acid at 1 wt % corresponds to what is needed for adsorption parallel to the surface. At the same concentration, the adsorbed amount of linoleic acid and linolenic acid indicates that they adsorb in multilayers. The chemisorbed amount estimated from static secondary ion mass spectroscopy (SIMS) measurements was found to be similar for the three unsaturated fatty acids. In the case of linolenic acid, it was found that the presence of water significantly alters the adsorption, most likely because of the precipitation of fatty acid/water aggregates. Furthermore, static SIMS results indicate that the amount of water used here inhibits the chemisorption of linolenic acid.
authors.affiliation: YKI, Institute for Surface Chemistry, Box 5607, SE-114 86, Stockholm, Sweden. sarah.lundgren@surfchem.kth.se
authors.forename: Sarah M
authors.initials: SM
authors.lastname: Lundgren
authors.forename: Karin
authors.initials: K
authors.lastname: Persson
authors.forename: Gregor
authors.initials: G
authors.lastname: Mueller
authors.forename: Bengt
authors.initials: B
authors.lastname: Kronberg
authors.forename: Jim
authors.initials: J
authors.lastname: Clarke
authors.forename: Mohammed
authors.initials: M
authors.lastname: Chtaib
authors.forename: Per M
authors.initials: PM
authors.lastname: Claesson
mesh_terms: D000327:Adsorption; D000473:Alkanes / Q000737:chemistry*; D005231:Fatty Acids, Unsaturated / Q000737:chemistry*; D012996:Solutions; D013232:Steel / Q000737:chemistry*; D013499:Surface Properties