Neutron reflectivity and atomic force microscopy studies on the effect of pH and solubilizate upon the structure of adsorbed cationic surfactant films on quartz

Schulz, JC; Nelson, A; Blom, ACM; War, GG

Neutron reflectivity and atomic force microscopy studies on the effect of pH and solubilizate upon the structure of adsorbed cationic surfactant films on quartz

Date

2005-11-27

Authors

Publisher

The Bragg Institute, Australian Nuclear Science and Technology Organisation

Abstract

We have examined the adsorbed layer morphology of cationic surfactant, tetradecyltrimethylammonium bromide (TTAB), on the hydrophilic quartz surface using atomic force microscopy (AFM) and neutron reflectometry (NR). We report on the effect of varying the surface charge of quartz by adjusting the bulk solution pH upon the adsorbed surfactant film structure. AFM results show that number density of globular (or spherical) TTAB aggregates on quartz increases, as the pH of the bulk solution is increased, reflecting the increase in surface charge of quartz. NR results also verify the AFM observations. We also report on the effect of the incorporation of a non-adsorbing solubilisate, naphthol, into the adsorbed surfactant film. In the bulk solution the incorporation of naphthol molecules into surfactant micelles promotes in micellar growth. Similarly, in the adsorbed surfactant film a transition to from globular to cylindrical surfactant aggregates was also observed. © 2005 The Authors

Description

Physical copy held by ANSTO Library at DDC 539.7217/2

Keywords

Adsorption, Atomic force microscopy, Crystal structure, Films, Layers, Micellar systems, Naphthols, Neutron beams, Neutron reflectors, pH value, Quartz, Sorptive properties, Surfactants

Citation

Schulz, J., Nelson, A., Blom, A., & War, G. (2005). Neutron reflectivity and atomic force microscopy studies on the effect of pH and solubilizate upon the structure of adsorbed cationic surfactant films on quartz. Paper presented at the Eighth International Conference on Neutron Scattering ICNS 2005, "Neutrons for structure and dynamics - a new era", Sydney Convention & Exhibition Centre, Sydney, Australia, 27 November-2 December 2005. In Final Programme and Abstract Book, (pp. 136-137).