Supra-long chain surfactants with double or triple quaternary ammonium headgroups

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• 作者：Tomokazu Yoshimura^a ; ^{yoshimura@cc.nara-wu.ac.jp} ; Nagisa Chiba^a ; Keisuke Matsuoka^b
• 关键词：Supra-long chain surfactant ; Multi-hydrophilic groups ; Critical micelle concentration ; Surface tension ; Free energy of micellization
• 刊名：Journal of Colloid and Interface Science
• 出版年：2012
• 期刊代码：125_00219797
• 类别：ch
• 出版时间：15 May, 2012
• 卷：374
• 期：1
• 页码：157-163
• 文件大小：387 K

摘要

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^鈭? 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.