title: Electrolyte effect on lamellar domain morphology in a nonionic surfactant solution below the Krafft temperature.
abstract: In our previous papers, we have studied the lamellar domain morphology in aqueous solutions of nonionic surfactants C16E6 and C16E7 below the Krafft temperature. In this study, electrolyte effects on lamellar domain morphology have been investigated by means of DSC, confocal microscope, small/wide-angle X-ray scattering (SAXS/WAXS). It has been found that vesicles in C16E7 solution are transformed to network structures by adding chaotropic ion Cl(-), F(-) and CH3COO(-), whereas the network structures in C16E6 solution are gradually changed to the vesicles with increasing kosmotropic ion SCN(-) concentration. Especially, we focused on the SCN(-) ion effects on the C16E6 system, and found that the characteristic morphology of cylinder-like domains were formed in a certain specific concentration range. In the SAXS observation in nm scale, we have also found that the repeat distance of lamellar structures in the C16E6/NaSCN solution is anomalously swollen when adding 1.2-2 mol/kg NaSCN, where the cylinder-like domains are formed. We have concluded that the cylindrical vesicles could be explained by the osmotic pressure difference due to the addition of NaSCN.
authors.affiliation: Department of Chemistry, Tokyo Metropolitan University , Hachioji, Tokyo 192-0397, Japan.
authors.forename: Youhei
authors.initials: Y
authors.lastname: Kawabata
authors.forename: Akira
authors.initials: A
authors.lastname: Murakami
authors.forename: Tadashi
authors.initials: T
authors.lastname: Kato