Polyelectrolyte/cationic surfactant

The effect of mixtures of surfactants and polyelectrolytes on spontaneous, water-catalysed hydrolysis (Fadnavis and Engberts, 1982) was mentioned in Section 4, but mixtures of functionalized polyelectrolytes and cationic surfacants are effective deacylating agents (Visser et al., 1983). Polymerized isocyanides were functionalized with an imidazole group and the deacylation of 2,4-dinitrophenyl acetate in the polyelectrolyte was speeded by addition of single or twin chain quaternary ammonium ion surfactants, up to a plateau value. Anionic surfactants had essentially no effect. It is probable that the cationic surfactants accelerate the reaction by increasing the deprotonation of the imidazole groups. 

K. Thalberg, B. Lindman, and G. Karlstrom Phase Behavior of Cationic Surfactant and Anionic Polyelectrolyte Influence of Surfactant Chain Length and Polyelectrolyte Molecular Weight. J. Phys. Chem. 95, 3370 (1991). 

Influent concentrations and residual concentrations of cationic surfactants, anionic surfactants, cationic polyelectrolyte, anionic polyelectrolyte, proteins, colloids, oxygen, ozone, detergents, suspended sohds, and so on, in the adsorptive bubble separation systems can be determined by the analytical methods reported in the literature (82,127-149). 

Samoshina, Y, Nylander, T, and Lindman, B., Cationic amphiphihe polyelectrolytes and oppositely charged surfactants at the silica-aqueous interface, Langmuir, 21,4490, 2005. 

CONCLUSIONS This Study shows that fluorescence probing techniques are useful and powerful tools for investigation of conformational transitions of polyelectrolytes as induced by cationic surfactants, pH or other means. Studies on the interaction of cationic probes with polyelectrolytes provide useful information on the intermediates that lie between A states and B states. It is concluded that the conformational transition induced by pH is a progressive process over several pH units. Studies on the interaction of cationic surfactants with PMA at pH 8 show that the aggregates formed are large loose structures, while the interior of the aggregate has a hydrophobicity that is similar to that of a micelle. 

It is interesting to note that while the cnc for cationic polyelectrolytes is lower on glass than on mica, the opposite is true for cationic surfactants [11]. The reason for this difference is that both electrostatic forces and hydrophobic interactions between neighboring surfactant tails drive the surfactant self-assembly on the surface. Since the lattice sites are closer to each other on mica than on glass, the self-assembly of the surfactant is more favorable on the former surface. 

Malovikova A, Hayakawa K, Kwak JCT. Surfactant—polyelectrolyte interactions. 4. Surfactant chain length dependence of the binding of alkylpyridinium cations to dextran sulfate. J Phys Chem 1984 88 1930-1933. 

Kogej K, Skerjanc J. Effect of polyelectrolyte on the aggregation of cationic surfactants in aqueous solutions. Acta Chim Slov 1998 45 443—453. 

Kogej K, Vrhovsek A, Skerjanc J. Interactions between anionic polyelectrolyte and cationic surfactant steady-state fluorescence measurements. In Noda I, Kokufuta E, eds. Polyelectrolytes. Osaka Yamada Science Foundation, 1999 288-291. 

The situation is very different for the more rigid polyelectrolyte xanthan. The foam films made with DTAB solutions are very unstable. When using DTAB or CTAB which alone give stable foam films, the incorporation of the polymers in the solutions also leads to unstable films. This behaviour is particular to the cationic surfactants indeed stable foam films can be made with nonionic surfactants and all the polymers. The data of Figure 8 for xanthan were obtained in this way.29 We have seen that in the case of cationic surfactants, mixed poly-... 

Photophysical studies on a conformational transition of PMA induced by cationic surfactants have been reported (7). The stretched PMA chain at pH 8 collapses on addition of cationic surfactants that is, the hydrophobic interactions between the cationic surfactants that are bonded to the PMA chain lead to refolding of the polymer chain, and thus provide a hydrophobic site for fluorescence probes at pH 8. The cationic polyelectrolyte poly(4-vinylpyridine) quatemized with n-dodecyl bromide (8 i0) or hexadecyl bromide (11) are also examples of hydrophobically modified polyelectrolytes. 

NOW Nowakowska, M., Szczubialka, K., and Grebosz, M., Interactions of temperature-responsive anionic polyelectrolytes with a cationic surfactant, J. Colloid Interface Sci., 265, 214, 2003. 

Figure 20.22. Phase separation in mixtures of a polyelectrolyte and an oppositely charged surfactant changes from associative (a,b), to no phase separation (c) and finally to segregative (d,e) as electrolyte is added. This example shows mixtures of a cationic surfactant, tetradecyltrimethylammonium bromide (TTAB), and an anionic polysaccharide, sodium hyaluronate (NaHy). (Redrawn from B. Lindman and K. Thalberg, in Interactions of Surfactants with Polymers and Proteins E. D. Goddard and K. P. Ananthapadmanabhan (Eds), CRC Press, Boca Raton, FL, 1993, p. 254)...

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