Self-Assembly and Rheological Properties of a Pseudogemini Surfactant Formed in a Salt-Free Catanionic Surfactant Mixture in Water

详细信息    查看全文

• 作者：Yan Li ; Hongguang Li ; Jinling Chai ; Mengjun Chen ; Qiao Yang ; Jingcheng Hao
• 刊名：Langmuir
• 出版年：2015
• 出版时间：October 20, 2015
• 年：2015
• 卷：31
• 期：41
• 页码：11209-11219
• 全文大小：841K
• ISSN：1520-5827

文摘

The surface and bulk properties of bola-type dicarboxylic acid (sebacic acid, SA) and zwitterionic surfactant tetradecyldimethylamine oxide (C₁₄DMAO) mixtures in aqueous solutions were studied. Surface tension measurements indicate a pronounced synergistic effect between SA and C₁₄DMAO. In bulk aqueous solutions, rich phase behavior was observed with a varied SA-to-C₁₄DMAO ratio (蟻) and a total surfactant concentration. Typically at 蟻 = 0.5, a novel pseudogemini surfactant (C₁₄-S-C₁₄) forms, driven by electrostatic interaction and hydrogen bonding. The C₁₄-S-C₁₄/H₂O system exhibits rich phase behavior induced by the transition of aggregates. With increasing concentration of C₁₄-S-C₁₄, one can observe a viscous L₁ phase, an L₁/L_伪 two-phase region where a birefringent L_伪 phase is on the top of an L₁ phase, a single L_伪 phase, and finally a mixture of an L_伪 phase and a precipitate. Microstructures formed in the L_伪 phases were determined by freeze鈥揻racture transmission electron microscopy (FF-TEM) and cryogenic-transmission electron microscopy (cryo-TEM) observations. Polymorphic aggregation behavior was observed with the formation of a variety of bilayer structures including unilamellar vesicles, onions, and open and hyperbranched bilayers. Rheological measurements showed that the L_伪 phases are viscoelastic and sensitive to temperature where a quick loss of viscoelasticity was observed at elevated temperature.