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In this paper, I delve into the physics of foams within the context of Enhanced Oil Recovery (EOR). Foams present a promising prospect for use in EOR, applicable to both conventional and non-conventional oil wells. A primary challenge faced by oil industry technologists is ensuring foam stability in porous media under harsh conditions of temperature, pressure, and salinity. To surmount these challenges, a profound understanding of the physicochemical mechanisms governing foam formation and stability at a microscopic level is required. In this article, I explore some fundamental aspects of foam physics that should be considered when developing foam systems for EOR. I conclude the paper by briefly discussing the use of machine learning in the design of foam-assisted EOR, and by highlighting the potential of smart foams in the oil industry. [Display omitted] [ABSTRACT FROM AUTHOR]

In this review I highlight a very sensitive experimental technique for the study of polymer-surfactant complexation: The electro-optic Kerr effect . This review does not intend to be exhaustive in covering the Kerr Effect nor polymer-surfactant systems, instead it aims to call attention to an experimental technique that, even if applied in a qualitative manner, could give very rich and unique information about the structures and aggregation processes occurring in mixtures of oppositely charged colloids. The usefulness of electric birefringence experiments in the study of such systems is illustrated by selected results from literature in hope of stimulating the realization of more birefringence experiments on similar systems. This review is mainly aimed at, but not restricted to, researchers working in polyelectrolyte-surfactant mixtures in aqueous solutions, Kerr effect is a powerful experimental tool that could be used in the study of many systems in diverse areas of colloidal physics. [ABSTRACT FROM AUTHOR]

We present an electric birefringence study of aqueous solutions of an intrinsically rigid polyelectrolyte, xanthan, and of mixed solutions with an oppositely charged surfactant, DTAB. The stationary electric birefringence as well as built-up and decay processes give information on the polarization mechanisms of the polyelectrolyte and on the role played by counterions. By adding a cationic surfactant (DTAB), that replaces the small Na+ counterions of the polymer, we could obtain further insights into the role of condensed counterions in these mechanisms. In some cases, anomalous birefringence signals appear, revealing a new polarization mechanism likely due to field-induced interactions within polymer-surfactant aggregates. [ABSTRACT FROM AUTHOR]

Abstract: X-ray reflectivity and adsorption kinetics of two different polyelectrolyte multilayers have been studied for polyelectrolyte multilayers (PEMs) composed of poly(diallyldimethyl ammonium chloride) (PDADMAC) and poly(sodium 4-styrenesulfonate) (PSS) polyelectrolyte pair and of poly(allylamine hydrochloride) (PAH) and PSS. The two characteristic times that describe the adsorption kinetics were found to be related to the X-ray reflectivity results, and their dependence on the number of adsorbed layers depends on the growth mechanisms (linear or superlinear) of the films. Therefore, it has been concluded that there is a correlation between the adsorption kinetics and the internal structure of the films. The time allowed for the adsorption of each polyelectrolyte controls the extension of the interdiffusion within the multilayer, and therefore whether the film is formed by stratified layers or it has a uniform structure except for the first and last layers. While the roughness of the (PDADMAC+PSS) n films strongly depends on the adsorption time, it is almost independent of it for the (PAH+PSS) n multilayer. This behavior correlates with that of the longest characteristic time of the adsorption kinetics. [Copyright &y& Elsevier]

Polyelectrolyte/surfactant systems of opposed charge generally show a plateau in surface tension isotherms as a function of surfactant concentration. The initial plateau is generally associated with the CAC (critical aggregation concentration). In the case of the PAMPS (10%)/DTAB system the plateau is not clearly defined. In this work dynamic surface tension (DST), and static and dynamic Kerr effect measurements are presented. These results suggest a polymer/surfactant non-cooperative association at surfactant concentrations below the CAC. At a surfactant concentration not long before that 1 mM a co-operative aggregation between neighborhood surfactant seems to take place. We associate this concentration with the CAC. Evidence in the relationship between dynamic surface adsorption and the equivalent point of charge (EP) is presented. At the EP concentration a plateau in the DST curves appears. For adsorption times above this plateau it seems that the adsorption mechanism is controlled by polymer diffusion and for times below the plateau by a mixed activation–diffusion mechanism with an energy barrier between 2 and 11 RT. Sensitivity and reliability of electro-optic techniques for this kind of study are emphasized. [Copyright &y& Elsevier]

Hypothesis Previous efforts to formulate smart foams composed of mixtures of PNIPAAm, a thermoresponsive uncharged polymer, and surfactants have failed because the surfactant displaces the PNIPAAm from the liquid-air interface, removing the thermal responsiveness. We hypothesized that thermoresponsive foams could be formulated with such a mixture if a charged surfactant were used in order to anchor an oppositely charged brush-type polyelectrolyte, for which PNIPAAm could be incorporated as side chains, to the interface. Experiments A brush-type negatively charged co-polyelectrolyte (Cop-L) with PNIPAAm as side chains was synthetized. Its mixtures with DTAB, a cationic surfactant, in aqueous solution were characterized by dynamic light scattering, surface tension and surface compression viscoelasticity measurements, as a function of both surfactant concentration and temperature. The foam stability and its responsiveness to temperature changes were studied with a homemade apparatus. Findings The Cop-L/DTAB mixtures were capable of producing thermoresponsive foams but only in a very narrow surfactant concentration (c s ) range, 0.3 < c s < 1.6 mM. The responsiveness is due to a modification of the interfacial compression elasticity induced by conformational changes of the Polyeletrolyte/surfactant aggregates at the interface. This is possible only for c s  < 1.6 because higher surfactant concentrations induce the polymer collapse at all temperatures, eliminating the thermal responsiveness. [ABSTRACT FROM AUTHOR]