Rheological experiments were carried out on aqueous dispersions of
cetyltrimethylammoniumhydroxynaphthalenecarboxylate (CTAHNC) as a function of temperature.
The results indicate the formation
of very long elongated wormlike micelles at temperatures higher than
about 50 °C, conferring to the system
a very high viscosity. This behavior is explained by the combined
effect of a large end cap energy and a
low ionization degree resulting from a strong binding of the weakly
soluble counterions. At lower temperature
the surfactant forms a much more fluid vesicle phase, which is observed
by videomicroscopy. Experiments
performed on mixtures of CTAHNC and of cetyltrimethylammonium bromide
(CTAB) show also a vesicle
to micelle transition for a ratio of CTAB/CTAHNC that decreases upon
increasing the temperature. The
rheological behavior of the micellar phase obtained by mixing CTAB and
CTAHNC is similar to that
obtained for other charged micellar solutions.
Based on n.m.r. spectroscopic results, a model to explain the specificity of sodium salicylate in producing viscoelasticity in dilute micellar solutions of cetyltrimethylamrnonium bromide is presented.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.