Vb. Fainerman et al., Dynamics and phase transition in adsorbed monolayers of sodium dodecyl sulfate/dodecanol mixtures, J PHYS CH B, 105(19), 2001, pp. 4324-4330
The coadsorption of sodium dodecyl sulfate (SDS)/n-dodecanol mixtures from
aqueous solution is theoretically and experimentally studied and compared w
ith the adsorption of the single components. The results of the surface pre
ssure adsorption kinetics are combined with imaging of the surface by Brews
ter angle microscopy (BAM). First-order phase transition with subsequent fo
rmation of condensed phase domains can occur in the adsorbed monolayers of
the mixtures over a large range of usual measuring conditions. A simple the
oretical model is developed for the description of the adsorption of the su
rfactant mixtures. The approach is based on the calculation of the surface
pressure isotherm of the mixture from the corresponding dependencies of the
single components, also including condensation (aggregation) of one compon
ent in the adsorbed monolayer. The approach can be used to calculate the dy
namic surface pressure for the diffusion adsorption mechanism. The results
obtained by the application of the theoretical model are in qualitative agr
eement with the experimental data. The theoretical results reproduce not on
ly the experimental findings that the condensed phase consists only of dode
canol but also the shift of the phase transition point to essentially short
er adsorption times.