title: Supra-long chain surfactants with double or triple quaternary ammonium headgroups.
abstract: Novel supra-long chain surfactants with double or triple quaternary ammonium salts (C(n)-2Am, C(n)-3Am, in which n represents a hydrocarbon chain length of 18, 20, and 22) were synthesized, and electrical conductivity and surface tension were used to characterize their properties depending on both the hydrocarbon chain length and number of hydrophilic groups. The Krafft temperatures decreased remarkably with an increase in the quaternary ammonium headgroups, resulting in a high solubility in water. The critical micelle concentration (cmc) increased with an increase in the number of quaternary ammonium moieties in the hydrophilic group, and the difference in the cmc was smaller for C(n)-2Am and C(n)-3Am than for C(n)-2Am and C(n)-Am of alkyltrimethylammonium bromide. The surface tension at the cmc was approximately 45 and 48 mN m(-1) for C(n)-2Am and C(n)-3Am with n=18-22, respectively. This indicated that the supra-long chain surfactants could not efficiently adsorb at the air/water interface and orient by themselves, as is known for conventional surfactants.
authors.affiliation: Graduate School of Humanities and Sciences, Nara Women's University, Kitauoyanishi-machi, Nara 630-8506, Japan. yoshimura@cc.nara-wu.ac.jp
authors.forename: Tomokazu
authors.initials: T
authors.lastname: Yoshimura
authors.forename: Nagisa
authors.initials: N
authors.lastname: Chiba
authors.forename: Keisuke
authors.initials: K
authors.lastname: Matsuoka
mesh_terms: D000327:Adsorption; D000388:Air; D004553:Electric Conductivity; D057927:Hydrophobic and Hydrophilic Interactions; D008422:Materials Testing; D008823:Micelles; D000644:Quaternary Ammonium Compounds / Q000138:chemical synthesis*; D012995:Solubility; D013500:Surface Tension; D013501:Surface-Active Agents / Q000138:chemical synthesis*; D013816:Thermodynamics; D014867:Water / Q000737:chemistry
chemical_list: D008823:Micelles; D000644:Quaternary Ammonium Compounds; D013501:Surface-Active Agents; D014867:Water