M. Hulden et B. Kronberg, MIXED ADSORPTION OF ANIONIC AND NONIONIC SURFACTANTS ON LATEX-PARTICLES, JCT, Journal of coatings technology, 66(835), 1994, pp. 67-77
Citations number
28
Categorie Soggetti
Chemistry Applied","Materials Science, Coatings & Films
A model is presented for the adsorption of a mixture of an anionic and
a nonionic surfactant on latex particles. The model is based on the L
angmuir equation for adsorption and the regular solution theory for mi
xed micelle formation. Good agreement between the experimental data an
d the calculated adsorption was obtained with a mixture of sodium dode
cyl sulphate (SDS) and nonylphenol ethoxylate (NPE10). The preferentia
l adsorption of the more surface active NPE10 is greatest at the onset
of micellization and diminishes as the total surfactant concentration
increases. The composition of the mixed surfactant at the surface gre
atly depends on the total surfactant concentration and on the surface
area/solution volume ratio. This is illustrated by the calculated adso
rption equilibria at different conditions. Addition of small amounts o
f organic solvents (e.g., coalescing aids) increases the critical mice
lle concentration (cmc) of NPE10 and decreases the cmc of SDS. The dec
rease in the difference between the cmc values of the two surfactants
is paralleled by a reduction in the preferential adsorption of the non
ionic surfactant in the presence of a coalescing-aid.