title: Oleic acid-based gemini surfactants with carboxylic acid headgroups.
abstract: Anionic gemini surfactants with carboxylic acid headgroups have been synthesized from oleic acid. The hydrocarbon chain is covalently bound to the terminal carbonyl group of oleic acid via an ester bond, and the carboxylic acid headgroups are introduced to the cis double bond of oleic acid via disuccinyl units. The surfactants exhibit pH-dependent protonation-deprotonation behavior in aqueous solutions. In alkaline solutions (pH 9 in the presence of 10 mmol dm(-3) NaCl as the background electrolyte), the surfactants can lower the surface tension as well as form molecular assemblies, even in the region of low surfactant concentrations. Under acidic (pH 3) or neutral (pH 6-7) conditions, the surfactants are intrinsically insoluble in aqueous media and form a monolayer at the air/water interface. In this study, we have investigated physicochemical properties such as the function of the hydrocarbon chain length by means of static surface tension, pyrene fluorescence, dynamic light scattering, surface pressure-area isotherms, and infrared external reflection measurements.
authors.affiliation: Department of Pure and Applied Chemistry, Faculty of Science and Technology, Tokyo University of Science, Chiba, Japan. k-sakai@rs.noda.tus.ac.jp
authors.forename: Kenichi
authors.initials: K
authors.lastname: Sakai
authors.forename: Naoki
authors.initials: N
authors.lastname: Umemoto
authors.forename: Wataru
authors.initials: W
authors.lastname: Matsuda
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Takamatsu
authors.forename: Mutsuyoshi
authors.initials: M
authors.lastname: Matsumoto
authors.forename: Hideki
authors.initials: H
authors.lastname: Sakai
authors.forename: Masahiko
authors.initials: M
authors.lastname: Abe
mesh_terms: D000143:Acids / Q000737:chemistry; D002264:Carboxylic Acids / Q000737:chemistry*; D005453:Fluorescence; D057446:Hydrodynamics; D006863:Hydrogen-Ion Concentration; D019301:Oleic Acid / Q000138:chemical synthesis* / Q000737:chemistry*; D011721:Pyrenes / Q000737:chemistry; D012996:Solutions; D013055:Spectrophotometry, Infrared; D013500:Surface Tension; D013501:Surface-Active Agents / Q000138:chemical synthesis* / Q000737:chemistry*; D013696:Temperature; D017186:Titrimetry
chemical_list: D000143:Acids; D002264:Carboxylic Acids; D011721:Pyrenes; D012996:Solutions; D013501:Surface-Active Agents; D019301:Oleic Acid; C030984:pyrene