Dw. Fuerstenau et M. Colic, Self-association and reverse hemimicelle formation at solid-water interfaces in dilute surfactant solutions, COLL SURF A, 146(1-3), 1999, pp. 33-47
Citations number
32
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
Using monodisperse anatase and hematite particles, such classical technique
s as colloid stability, zeta potential and wettability measurements along w
ith fluorescence spectroscopy show that anionic alkyl sulfate and sulfonate
surfactants first associate into hemimicelles at the interface and cause t
he particles to begin to coagulate and to become hydrophobic. Maximum coagu
lation and hydrophobicity occur under conditions where the zeta potential i
s zero. At higher surfactant concentrations, the particles redisperse and r
egain their hydrophilicity. Upon reversal of the zeta potential, the adsorb
ed surfactant ions appear to form hemimicelles with reverse orientation or
bilayers, at surfactant concentrations significantly lower than the critica
l micelle concentration. The results of these experiments correlate well wi
th spectroscopic and adsorption measurements. (C) 1999 Elsevier Science B.V
. All rights reserved.