Y. Hendrikx
May 1, 1979
Citations
0
Influential Citations
17
Citations
Journal
Journal of Colloid and Interface Science
Abstract
Films of docosyltrimethylammonium bromide, sodium docosyl sulfate, and mixtures of both constituents spread on aqueous solutions (pH = 5.5) have been investigated. The results give evidence of electrostatic interactions taking place in the mixed films. The effect of cetyl alcohol upon the equimolecular films (A) of cationic and anionic surfactants has also been studied. The cetyl alcohol and “A mixture” are in a 11 ratio. From surface pressure and surface potential measurements, it appears that there is no interaction between cetyl alcohol and the equimolecular “A mixture.” There is either an ideal mixture or two nonmiscible compounds. From the surface potential measurements, we have deduced the values of the permanent dipole moments of cetyl alcohol and docosyltrimethylammonium bromide molecules. As a matter of fact, the surface potential of the mixed films, with a surface density higher than the collapse density, decreases as a function of the salt activity in the substrate, namely CaCl2. The pH is maintained at 7.5 by adding NaOH.