J. Zhang, G. Xu, Y. Zhou, T. Zhou and X. Zhai,Polyhedral vesicles with crystalline bilayers formed from catanionic surfactant mixtures of fluorocarbon and hydrocarbon amphiphiles,J. Colloid Interface Sci.,2013,407(1), 318-326.

Salt-free catanionic mixtures of perfluorononanoic acid (C8F17COOH) and tetradecyltrimethylammonium hydroxide (TTAOH) in aqueous solution show rich and interesting self-assembly properties. With the addition of TTAOH to a C8F17COOH solution, a structural transition from polyhedral vesicles with crystal-line bilayers to spherical vesicles with fluid bilayers was observed at room temperature, which was demonstrated by cryo- and FF-TEM observations, DSC and WAXS measurements. It is interesting that both uni-lamellar and multi-lamellar polyhedral vesicles were formed in these fluoro- and hydrocarbon catanionic surfactant mixtures. SAXS measurements were performed to determine the interlamellar spacing of the multilamellar polyhedral vesicles. The driving force for the formation of the polyhedral vesicles was the crystallization of the C8F17COO- - TTA+ ion pairs in the bilayers, which induced the excess anionic surfactants to be segregated and concentrated to produce the vertices of the polyhedral vesicles. Besides, the rheological results show that the rheological properties of the C8F17COOH/TTAOH system are greatly affected by the fluorocarbon chains due to their high rigidity and Krafft boint. The solutions consisting of polyhedral vesicles have high viscoelasicity and high yield stress values while spherical vesical solutions are not viscoelastic.