Properties of Aqueous Solutions of Polyelectrolytes and Surfactants of Opposite Charge: Surface Tension, Surface Rheology, and Electrical Birefringence Studies

Abstract

We describe the dynamic behavior of both surface and bulk of mixed aqueous solutions of surfactants and polymers of opposite electrical charges. We evidence the importance of the point of equivalence of charges (EP), which occurs well before precipitation in our systems. Close to EP, an adsorption barrier, possibly due to charge reversal, starts to build up at the surface. In the bulk, the surfactant not only screens the polymer charges but is likely to start binding to the polymer chains.

Complexation of oppositely charged polyelectrolytes and surfactants in aqueous solutions. A review

“…Binding of surfactant to polymer occurs at very low polymer and surfactant concentrations [23], but does not lead to appreciable changes except at surfaces: the surface tension of the solutions falls to small values [1]. Significant changes in bulk properties are seen only when the binding of surfactant to polymer becomes cooperative : this occurs above a surfactant critical aggregation concentration (cac) in general one or two orders of magnitude lower than the critical micelle concentration (cmc) of the pure surfactant solution.…”

“…At large polymer concentrations, the autocorrelation function g (1) (q, t) transforms into a stretched exponential [23]:…”

Equilibrium and dynamic aspects of dodecyltrimethylammonium bromide adsorption at the air/water interface in the presence of λ-carrageenan

“…On the other hand, it has been reported [28] that the surface tension for an aqueous solution of DTAB can be affected by the presence of iota-carrageenan at concentrations as low as 1 ppb. Furthermore, these data show a dependence of the CAC value on the polyelectrolyte concentration; there is some disagreement [9,27] on whether such correlation should exist. Such a result would confront the thermodynamic adsorption model, which is based simply on an exchange of the surfactant counterions for the polyelectrolyte ions, which should keep the same partition of the surfactant molecules between micelles and air/liquid interface.…”

“…Bergeron and co-workers [6] studied the anionic polyelectrolyte poly(styrenesulfonate) (PSS) with the cationic surfactant DTAB through dilational and shear interfacial rheological measurements, and they could correlate their results with the foamability and foam stability of the system. Langevin and co-workers [7][8][9] investigated the surface viscoelasticity of systems containing different oppositely charged polyelectrolytes and surfactants and they were able to attest the influence on foam stability. They concluded that, in the case of their systems, surface rheology properties changed with macromolecule backbone rigidity [8] and that the adsorption kinetics depended on whether the system was below or above the equivalent point of charges [9].…”

“…Langevin and co-workers [7][8][9] investigated the surface viscoelasticity of systems containing different oppositely charged polyelectrolytes and surfactants and they were able to attest the influence on foam stability. They concluded that, in the case of their systems, surface rheology properties changed with macromolecule backbone rigidity [8] and that the adsorption kinetics depended on whether the system was below or above the equivalent point of charges [9]. On the other hand, Ivanov et al [10] stated that the correlation between the dynamic properties of the interface and the dispersion stability should be analyzed with caution.…”