Surfactant-polymer interactions adsorption

Polymers and surfactants are used together sometimes to obtain desirable effects. Polymer-surfactant interactions in solution and at the interfaces can change the interfacial properties of the solid directly or indirectly. It is shown that depending on the nature of the polymer and the surfactant, polymers can affect flotation of quartz by affecting the adsorption of the surfactant on it [7]. 

The striking difference of behavior between SDS and TTAB as far as changes of CMC and 3 are concerned suggest that the polymer-surfactant interaction occurs at the level of the surfactant ionic head group and does not involve the surfactant alkyl chain. This is turn means that the penetration of the polymer in the micelle will be restricted to the head group region, with little if any at all, penetration of the polymer in the micelle hydrophobic interior. Thus, the polymer surfactant interaction can be looked at as an adsorption of the polymer chain on the micelle surface. ... 

A fundamental question as to the nature of polymer-surfactant interaction arises from the large difference between the mass of polymer and that of surfactant molecules. The adsorption concept emphasizes that the polymer is a large unit and it has many sites available for surfactant binding. In the complex formation model, the stress is on the elementary process between one polymer site and the surfactant molecule, disregarding the fact that the polymer sites are linked with each other in the polymer chain. 

Another promising domain of investigation on polymer—surfactant interactions concerns the adsorption behavior at the solid-liquid interface of the different partners of the interaction (i.e., surfactant, polymer, and resulting complex). Increasing effort is devoted in understanding what happens at the solid-liquid interfaces, as numerous commercial applications of polymer-surfactant mixtures are a consequence of their interaction with... 

The concentration regime at which polymer—surfactant interaction is studied. For a low-concentration regime, studies are focused on the mechanism of interaction between the polymer and the surfactant. The adsorption behavior of polymers, surfactants, and their possible resulting complexes at various interfaces (liquid-air, solid-liquid) primarily concern those dilute conditions. On the other hand, the association between polymers and surfactants for high-concentration ranges finds broad practical applications as a consequence of complex phase behaviors [9,11]. 

Polymers with which we will deal throughout this chapter are water soluble. They can be either ionic or nonionic. Some of them are synthetic, others are of biological origin (proteins, for instance). Both homopolymers and heteropolymers exist. Some polymers own amphiphilic monomers that induce surface-active properties to the whole polymeric structure. Water plays a very important role in determining the polymer properties in solution. The properties are also greatly modified by the addition of salts or by a pH modification. Frequently encountered nonionic polymers in polymer-surfactant interactions and their subsequent adsorption behavior at solid surfaces are poly(ethylene oxide) (PEO), poly(vinyl pyrrolidone) (PVP), polyacrylamide, and poly(vinyl alcohol). 

The ability of surfactants to form complexes with polymer chains may also affect the ultimate properties and stability of the resulting polymer, especially when the macromolecule exhibits some affinity for or reactivity with water. Perhaps the best documented case of the effect of surfactant on latex stability is that of polyvinyl acetate. The stability of PVAc latexes has been found to vary significantly depending on the surfactant employed in its preparation. It has also been found that PVAc could be dissolved in concentrated aqueous solutions of SDS and that it did not precipitate on dilution. The results suggest that, in this case at least, solubilization did not occur in the micelle, but that extensive adsorption of surfactant onto the polymer chain was required. They also indicate that a strong, stable PVAc-SDS complex is formed that produces a water-soluble structure that is essentially irreversible, imlike normal micelle formation. Cationic and nonionic surfactants had little or no solubilizing effect under identical conditions, indicating the specific nature of many, if not most, polymer-surfactant interactions. 

One complication that arises with thin-liquid foam film studies is the need to have surface-active components present in order to stabilize the films. Without adequate film stability, measmement of the interactions between the two air-water interfaces caimot be accomplished. These surface-active species provide film stability via surface elasticity and repulsive force interactions between the interfaces (i.e., DLVO-type interactions). In addition, surfactants may interact with polymers added to the system, which can mediate and change the polymer configuration, surface adsorption, and thin-film interactions. Therefore, to determine the role of a polyelectrolyte one must understand independently the various interfacial and polymer-surfactant interactions. Theodoly and colleagues [18,19] have accomplished this through a judicious choice of combined polymer-surfactant mixtures. Two systems... 

The present study investigates the adsorption and trapping of polymer molecules in flow experiments through unconsolidated oil field sands. Static tests on both oil sand and Ottawa sand indicates that mineralogy plays a major role in the observed behavior. Effect of a surfactant slug on polymer-rock interaction is also reported. Corroborative studies have also been conducted to study the anomalous pressure behavior and high tertiary oil recovery in surfactant dilute-polymer systems(ll,12). 

Recent investigations have shown that the behavior and interactions of surfactants in a polyvinyl acetate latex are quite different and complex compared to that in a polystyrene latex (1, 2). Surfactant adsorption at the fairly polar vinyl acetate latex surface is generally weak (3,4) and at times shows a complex adsorption isotherm (2). Earlier work (5,6) has also shown that anionic surfactants adsorb on polyvinyl acetate, then slowly penetrate into the particle leading to the formation of a poly-electroyte type solubilized polymer-surfactant complex. Such a solubilization process is generally accompanied by an increase in viscosity. The first objective of this work is to better under-stand the effects of type and structure of surfactants on the solubilization phenomena in vinyl acetate and vinyl acetate-butyl acrylate copolymer latexes. 

This section summarizes the factors affecting surfactant-polymer interaction, including electrolyte concentration, alcohol, oil, polymer concentration, competitive adsorption, and phase trapping. 

The colloidal stabilization of aqueous dispersions by polymer surfactants is believed to be a result of the adsorption of the amphiphilic macromolecules on the particle surface. This adsorption results in the formation of mono- or multi-layers of certain structure and thickness which provide sterical and/or electrostatic stabilization effects [1-5], Polymer adsorption from aqueous solution on a particle surface is a result of specific interactions of various active sites on the particle surface with corresponding sites (groups) of the macromolecule. Therefore the adsorption behaviour and the colloidal stabilization may be used as a sensitive approach (tool) to elucidate the effects of the polymers structural differences on their behaviour on the liquid-solid interface [6-9],... 

Anionic sulfonated polyacrylamide (PAMS) is also found to increase amine flotation of quartz. Although PAMS does not adsorb on the negatively charged quartz and cause no direct activation of amine adsorption, the polymer-surfactant electrostatic interaction can lead to the formation of complexes. This polymer-surfactant complex can reduce the armoring of bubbles and lead to flotation. The anionic polymer can also bridge the adsorbed amine to the amine on the bubble surface and enhance flotation under saturated adsorption conditions. The hydration effect of the polymer may also be responsible for the enhanced flotation in this case. 

The interfacial behaviour of surfactant-polymer mixtures, utilized for example in the stabilization of suspensions, depends on a complex interplay between different pair interactions. Addition of a polymer can either remove surfactant from a surface or enhance its adsorption, and vice versa, depending on the relative stability of the polymer-surfactant complexes in solution and at the interface. 

Physicochemical properties of polymer surfactants that present macromolecules with both hydrophobic and hydrophilic fi agments are to be considered as stabilizers of ultradispersed state in all the above-cited processes. Along with the topochemistry, interactions which condition the morphology of future nanocomposites must also be considered. The stabilization mechanism is based on structural and mechanical constituents of stability in dispersed systems and spatial networks of the coagulation structure type and formation of adsorption-solvate structured films on nanoparticle surface. 

Hirano S, Hirochi K, Hayashi K, Mikami T, Tachibana H. Cosmetic and pharmaceutical uses of chitin and chitosan. In Gebelein CG, Cheng TC, Yang VC, eds. Cosmetic and Pharmaceutical Apphcations of Polymers. New York Plenum Press, 1991 95-104. Ananthapadmanabhan KP. Surfactant solutions adsorption and aggregation properties. In Goddard ED, Ananthapadmanabhan KP, eds. Interactions of Surfactants with Polymers and Proteins. Boca Rat. FL CRC Press, 1993 5-58. 

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