Dynamic and thermodynamic aspects of polymer-surfactant interactions. The SDS-PVP-water system.

The water-PVP (polyvinylpyrrolidone)-SDS (sodium dodecylsulfate) system was investigated by ultrasonic relaxation measurements. In water-PVP mixts. the relaxation time is independent on the polymer content, whereas in water-SDS solns. it decreases on increasing the amt. of surfactant in micellar form. In the ternary water-PVP-SDS systems, at fixed PVP content, 3 different regions were obsd. on increasing the amt. of SDS: namely, at very low surfactant content the relaxation time, τ1, increases then remains nearly const. and finally decreases. The above behavior was ascribed to surfactant binding onto the polymer and to micelle formation, resp. By analyzing the dependence of relaxation time(s) on compn., it was possible to divide the investigated region in 3 domains (i.e. non-interaction region, polymer-surfactant interaction region, and micellar region). A phase diagram for the above system was drawn according to the exptl. kinetic results. From the data obtained by ultrasonic relaxation expts. the no. of SDS mols. bound to PVP, 〈m〉, was evaluated and the Gibbs energy of binding, [ΔGbind/〈m〉], calcd

Polymer-Surfactant Interaction: Non ionic Polymer with SDS and DTABr

Polymer-surfactant interactions in water-SDS-polyvinylpyrrolidone (PVP), water-SDS-polyoxyethylenglycol (PEO), water-(DTABr)-(PEO) and in water-SDS-polyoxypropylenglycol (PPO), systems have been investigated by ultrasonic relaxation, adiabatic compressibility and viscosity measurements. Both the hydrodynamic and thermodynamic properties show significant changes at the critical association concentration in presence of polymer. As to the kinetic behaviour, investigation on systems containing PEO or PVP indicates the occurrence of a region where relaxation times are nearly constant. For the low molecular weight PPO polymer this effect has not been observed. Such differences have been ascribed to the minimum polymer chain length effect, required for the binding of surfactant aggregates on the polymer backbone. The dynamics of polymer-surfactant interactions has been discussed in terms of a kinetic model, previously proposed

Dielectric Behaviour of Octyl-beta-D-Glucopyranoside Micelles in water and in water-glycine solutions.

The dielec. permittivity, viscosity, and d. of octyl - beta-D-glucopyranoside (OBG) and glycine (G) aq. solns. (with different OBG/G mol. ratios) were measured as a function of surfactant concn. and temp. to study the effect of the amino acid on the surface of the glucoside micelles. The amino acid shows an appreciable influence on the thermodn. stability of the surfactant aggregates. However viscometric, volumetric, and dielec. results indicate that glycine is not involved in the micellar surface. Such a result indicates that the stabilization of the OBG micellar assemblies (obsd. previously) is due mainly to a decrease of the soly. of the hydrocarbon tail and/or to an increase of the interfacial tension between the micellar oil core and the solvent rather than to short-range interactions between glycine and OBG polar head groups