title: Self-Assembly and Rheological Properties of a Pseudogemini Surfactant Formed in a Salt-Free Catanionic Surfactant Mixture in Water.
abstract: 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 (ρ) and a total surfactant concentration. Typically at ρ = 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/Lα two-phase region where a birefringent Lα phase is on the top of an L1 phase, a single Lα phase, and finally a mixture of an Lα phase and a precipitate. Microstructures formed in the Lα phases were determined by freeze-fracture 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 Lα phases are viscoelastic and sensitive to temperature where a quick loss of viscoelasticity was observed at elevated temperature.
authors.affiliation: College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Shandong Normal University , Jinan, Shandong Province 250014, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.affiliation: Laboratory of Clean Energy Chemistry and Materials, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences , Lanzhou, Gansu Province 730000, China.
authors.forename: Hongguang
authors.initials: H
authors.lastname: Li
authors.affiliation: College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Shandong Normal University , Jinan, Shandong Province 250014, China.
authors.forename: Jinling
authors.initials: J
authors.lastname: Chai
authors.affiliation: Key Laboratory of Colloid and Interface Chemistry & Key Laboratory of Special Aggregated Materials, Shandong University, Ministry of Education , Jinan, Shandong Province 250100, China.
authors.forename: Mengjun
authors.initials: M
authors.lastname: Chen
authors.affiliation: Key Laboratory of Colloid and Interface Chemistry & Key Laboratory of Special Aggregated Materials, Shandong University, Ministry of Education , Jinan, Shandong Province 250100, China.
authors.forename: Qiao
authors.initials: Q
authors.lastname: Yang
authors.affiliation: Key Laboratory of Colloid and Interface Chemistry & Key Laboratory of Special Aggregated Materials, Shandong University, Ministry of Education , Jinan, Shandong Province 250100, China.
authors.forename: Jingcheng
authors.initials: J
authors.lastname: Hao