Polyelectrolyte-surfactant interactions solution

Particles or macroscopic solid surfaces are present in most of the applications mentioned above. Hence it is important to know how polyelectrolytes and surfactants interact with each other at solid-liquid interfaces. Due to the slow equilibration in many polyelectrolyte-surfactant systems, particularly at interfaces, it is fruitful to distinguish between two situations. In the first case the polyelectrolyte is initially adsorbed at the solid-liquid interface and then the polyelectrolyte is removed from the solution before the surfactant is added. This mimics the situation in many cleaning applications. Most of the studies concerned with polyelectrolyte-surfactant interactions at solid-liquid interfaces belong to this category. 

A variational theory which includes all these different contributions was recently proposed and applied for completely stretched polyelectrolyte stars (so-called porcupines ) [203, 204]. As a result, the effective interaction V(r) was very soft, mainly dominated by the entropy of the counterions inside the coronae of the stars supporting on old idea of Pincus [205]. If this pair potential is used as an input in a calculation of a solution of many stars, a freezing transition was found with a variety of different stable crystal lattices including exotic open lattices [206]. The method of effective interactions has the advantage to be generalizable to more complicated complexes which are discussed in this contribution-such as oppositely charged polyelectrolytes and polyelectrolyte-surfactant complexes-but this has still to be worked out in detail. 

Polymer surfactant interaction has been examined by using sodium 2-(N-dodecyIamino)naphthalene-6-sulphonate as a probe. Solute-solvent interaction of free base phthalocyanine has been examined in both polyethylene and polystyrene by the effect of pressure on spectroscopic hole burning s Fluorescence has been used to indicate the onset of aggregation in water soluble polymers s interaction of pyrenylmethyltributylphosphonium bromide with single strand polynucleotides , and the interaction of indole compounds with synthetic polyelectrolytes. ... 

We now turn to the more complex situation where both polyelectrolytes and surfactant are present in solution and adsorption is allowed to occur from this mixture. Polyelectrolyte and surfactant mixtures are used in numerous applications such as pharmaceuticals, laundry, and cosmetics, just to mention a few [4], Sometimes polyelectrolytes and surfactants are unintentionally mixed and due to mutual interaction provide unexpected properties to the mixture. Sometimes they are purposefully added together to fill the function of changing the properties and feel of surfaces, e.g., hair or fabrics, or to act as deposition aids. It is thus important to understand how these mixtures act when they are first mixed in bulk and subsequently transferred to a surface, and how the properties of polyelectrolyte-surfactant aggregates formed in bulk correlate with the properties of such aggregates adsorbed at a solid-liquid interface. Further, it is necessary to learn what happens with the polyelectrolyte-surfactant mixture at the surface when it is diluted with water. 

The effect of simple salt on the surfactant binding confirms the electrostatic nature of the surfactant ion-polyion interactions (step 1, Scheme 1). Any increase in the ionic strength of solution shifts the onset of binding toward higher free surfactant concentrations (compare isotherms in water, 0.01 M, and 0.1 M NaCl, Figure 6) and decreases the amount of bound surfactant. These observations can be related to the screening influence of the simple salt, which acts to diminish the electrostatic interactions between surfactant cations and polyanions. This is also well documented in the literature for a variety of polyelectrolyte-surfactant pairs [26-29],... 

Many naturally occurring random-coil polyelectrolytes of a single charge type, including some carbohydrates, pectins, and keratins, are anionic and exhibit the same general surfactant interactions as their synthetic cousins. Proteins, on the other hand, are amphoteric polyelectrolytes, which possess a net charge character (anionic or cationic) that depends on the pH of the aqueous solution. Unhke most synthetic polyelectrolytes, natural polyelectrolytes such as proteins and starches often have well-defined secondary and tertiary structures in solution that can affect, and be affected by, surfactant... 

Thalberg, K. and Lindman, B., Polyelectrolyte-ionic surfactant systems phase behavior and interactions, in Surfactants in Solution, Mittal, K. and Shah, D.O. (eds.). Plenum Press, New York, 1991, pp. 11, 243. 

The polyelectrolyte coated surface is uncharged, or in the case of AM-MAPTAC-30 weakly positively charged, before SDS is added. When SDS associates with an uncharged polyelectrolyte layer it will result in a recharging of the interface which results in the development of an electrostatic double layer and a less favorable polyelectrolyte-surface interaction. Thus, the polyelectrolyte-surfactant association at the mica surface is counteracted by electrostatic forces. Instead, it is driven by the hydrophobic interaction between the surfactant tails. This is confirmed by the cooperative nature of the association process observed for all polyelectrolyte-surfactant systems studied in this report. It is well known that hydrophobic interactions are very important also for the association between polyelectrolytes and surfactants in bulk solutions as demonstrated by the cooperativity of this process [16]. The... 

As described above, interactions between oppositely charged surfactants and polyelectrolytes in aqueous solutions can lead to associative phase separation, where the concentrated phase assumes the form of a viscous liquid, gel, liquid crystal or precipitate. This behavior has been exploited to form gel particles, which have been prepared by drop-wise addition of cellulose-based polycation solution (chitosan or-, N,N,N-trimethylammonium derivatized hydroxyethyl-cellulose) to anionic (sodium dodecyl sulfate, sodium perfluorooctanoate) and cationic (cetyltrimethylammonium bromide/sodium perfluorooctanoate) surfactant solutions [76-80]. 

The measurement of the surface tension of SDS solutions at constant polymer additions was performed to investigate any possible interactions between SDS and the polymers used in these experiments. The results, shown in Figure 2, indicate no interaction between SDS and either PAA or PAM. Interactions between similarly charged surfactant and polyelectrolyte are not common as electrical effects frequently dominate to prevent any hydro-phobic or hydrogen bonding interaction. The hydrophilic nature of the amide dipole of polyacrylamides has been suggested (11) as a possible factor in preventing interaction with sodium dodecylsulfate,... 

It is known that interactions between ionic surfactants and polyions with the opposite charge lead to the formation of soluble colloidal complexes. The polyelectrolyte chain binds to surfactant molecules through Coulombic attractions, and the hydrophobic moieties of the surfactant molecules stabilize the complexes due to hydrophobic interactions in the aqueous solution (Morris and Jennings, 1976 Satake and Yang, 1976 Osica etal., 1977 Fendler, 1982 Hayakawa et al., 1983 Jonsson et al, 1998). 

There is a range of parameters other than polyelectrolyte charge density that has an important influence on the generated surface interactions, for instance, counterion valency and ionic strength of solution [121-123], the order of addition of polyelectrolyte and salt [124], polyelectrolyte concentration [125], presence of surfactants [31, 119, 126], and finally, the chemical structure of the polyelectrolyte itself [127]. A rich literature is available on these topics (see Ref. [115] and references therein). 

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