In this paper, we report a self-assembly of surfactant molecules at the interface of air/hygroscopic quaternary ammonium salts such as tetrabutylammonium acetate (TBAAc), tetrabutylammonium bromide (TBAB), and tetrabutylammonium nitrate (TBAN), where they show different hygroscopicity, TBAAc > TBAB = TBAN. Homogeneously dissolved surfactants rearrange themselves when they contact air due to high moisture adsorption behavior of such organic salts. Highly ordered lamellar phases with different lattice spacings have been observed when surfactants with long alkyl chains were used. Alkylammonium halides form monolayers, while neutral alkylamines forms bilayers based upon basal spacings of their X-ray diffraction patterns. The change in basal spacings in lamellar patterns, the alkyl chain conformation of surfactants, and H-bonding property of neutral amine surfactants are discussed in detail.
Revised: November 10, 2005 |
Published: December 15, 2003
Citation
Shin Y., L.Q. Wang, G.E. Fryxell, and G.J. Exarhos. 2003.Hygroscopic Growth of Self-Assembled Layered Surfactant Molecules at the Interface between Air and Organic Salts. In Self-Assembled Nanostructured Materials: Symposium held April 22-25, 2003, San Francisco, California, U.S.A. Materials Research Society Symposium Proceedings, edited by Lu, Yunfeng, 775, 141-145. Warrendale, Pennsylvania:Materials Research Society.PNNL-SA-38544.