Self-Consistent Mean Field Calculations of Polyelectrolyte-Surfactant Mixtures in Solution and upon Adsorption onto Negatively Charged Surfaces

Abstract

Self-Consistent Mean-Field Calculations (SCF) have provided a semi-quantitative description of the physico-chemical behavior of six different polyelectrolyte-surfactant mixtures. The SCF calculations performed showed that both the formation of polymer-surfactant in bulk and the adsorption of the formed complexes onto negatively-charged surfaces are strongly affected by the specific nature of the considered systems, with the polymer-surfactant interactions playing a central role in the self-assembly of the complexes that, in turn, affects their adsorption onto interfaces and surfaces. This work evidences that SCF calculations are a valuable tool for deepening on the understanding of the complex physico-chemical behavior of polyelectrolyte-surfactant mixtures. However, it is worth noting that the framework obtained on the basis of an SCF approach considered an equilibrium situation which may, in some cases, be far from the real situation appearing in polyelectrolyte-surfactant systems.

Physicochemical Aspects of the Performance of Hair-Conditioning Formulations

“…Nowadays, different theoretical approaches, mainly based on the use of mean-field selfconsistent calculations, have been used for the in silico prediction of the performance of different model conditioning formulations [11,[71][72][73][74]. The results obtained following the abovementioned theoretical approaches are generally in good accordance with the experimental findings [7,45,46].…”

“…These surfactants are considered to be the most efficient in the cleaning of sebum fats and dirt in general. However, an excessive deposition of this surfactant onto the surface of the hair fibers during the washing process may increase the number of negative charges, which would be detrimental for the conditioning process as result of the increase in the friction [7,[41][42][43][44][45][46]. • Cationic surfactants.…”

“…The most common among this type of surfactants are those based on ethylene oxides, the so-called ethoxylated surfactants. Another important class of nonionic surfactants are "multihydroxy" molecules, such as glycol esters, glycerol and polyglycerol esters, glycosides and polyglycosides and sucrose esters [7,46]. • Zwitterionic surfactants.…”

“…They have good foaming, detergent and wetting properties and are very mild, presenting excellent dermatological properties; therefore, they are used to reduce the aggressiveness of anionic surfactants. The most common are N-alkyl betaines, derived from trimethylglycine (betaine) [45,46,48].…”

Evaporation of Sessile Droplets of Polyelectrolyte/Surfactant Mixtures on Silicon Wafers

“…The increase in the turbidity of the mixtures for the highest surfactant concentrations can be only explained by the formation of solid particles due to the polyelectrolyte-surfactant association. This is only possible assuming that the formation of kineticallytrapped aggregates occurs due to the Marangoni stresses associated with a local excess of surfactant molecules during the initial stages of the mixing procedure [64][65][66][67][68]. These kinetically-trapped aggregates remain intact upon dilution and present a quasi-neutral inner core formed mainly of surfactant molecules bound to the polymer monomers, where the external region appears positively charged, i.e., formed by non-associated monomers.…”