Microemulsions interactions

In an effort to investigate the universality of this t rpe of polymer-microemulsion interaction, an anionic surfactant system was studied. Two sulfonate surfactants were chosen to enable variation of the hydrophile-lipophile characteristics of the surfactant couple and in turn of the mlcroemulslon. The... 

Let us consider qualitatively the effect of the microemulsion composition on the sulfonate-microemulsion, sulfonate-adsorbent and microemulsion-adsorbent interactions. We assume that the interaction potential between a single sulfonate anion and its nearest-neighbor molecules and ions in the oil-brine interfacial region in the microemulsion is nearly constant within the appropriate series of microemulsions (e.g. A, B, C and D). As a first approximation therefore we consider the sulfonate-microemulsion interactions to be unaffected by microemulsion composition within such a series. 

The larger adsorptions from the TRS 10-410/n-butanol and PDM-334/n-butanol microemulsions may be due to weaker interactions between the respective sulfonate anion and its nearest-neighbor molecules and ions as a result of the very low brine content in these microemulsions these microemulsions exhibit inordinately high interfacial tensions versus brine. It appears that adsorption from the n-butanol microemulsions may begin to approach the adsorption behavior exhibited by the nonane sulfonate solutions. It may be that the assumption that sulfonate-microemulsion interactions are equivalent within each microemulsion series such as A, B, C and D holds adequately only for the glycol ether microemulsions. 

M.E. Cates in Proc. ACS-Symp. on Polymeric Microemulsions and Polymer-Microemulsion Interaction, New Orleans, (1987)... 

It is of particular interest to be able to correlate solubility and partitioning with the molecular stmcture of the surfactant and solute. Likes dissolve like is a well-wom plirase that appears applicable, as we see in microemulsion fonnation where reverse micelles solubilize water and nonnal micelles solubilize hydrocarbons. Surfactant interactions, geometrical factors and solute loading produce limitations, however. There appear to be no universal models for solubilization that are readily available and that rest on molecular stmcture. Correlations of homologous solutes in various micellar solutions have been reviewed by Nagarajan [52]. Some examples of solubilization, such as for polycyclic aromatics in dodecyl sulphonate micelles, are driven by hydrophobic... 

Cosolvents ana Surfactants Many nonvolatile polar substances cannot be dissolved at moderate temperatures in nonpolar fluids such as CO9. Cosolvents (also called entrainers, modifiers, moderators) such as alcohols and acetone have been added to fluids to raise the solvent strength. The addition of only 2 mol % of the complexing agent tri-/i-butyl phosphate (TBP) to CO9 increases the solubility ofnydro-quinone by a factor of 250 due to Lewis acid-base interactions. Veiy recently, surfac tants have been used to form reverse micelles, microemulsions, and polymeric latexes in SCFs including CO9. These organized molecular assemblies can dissolve hydrophilic solutes and ionic species such as amino acids and even proteins. Examples of surfactant tails which interact favorably with CO9 include fluoroethers, fluoroacrylates, fluoroalkanes, propylene oxides, and siloxanes. 

Fluorescence investigations of the partitioning of the aromatic fluorophore Prodan in water/AOT/n-heptane, water/DTAB/n-hexanol/n-heptane, and water/CTAB/n-hexanol/n-heptane microemulsions proved that this molecule, as a consequence of a variety of non-covalent interactions, is distributed in several distinct micellar domains [140]. 

By dynamic light scattering it was found that, in surfactant stabilized dispersions of nonaqueous polar solvents (glycerol, ethylene glycol, formamide) in iso-octane, the interactions between reversed micelles are more attractive than the ones observed in w/o microemulsions, Evidence of intermicellar clusters was obtained in all of these systems [262], Attractive intermicellar interactions become larger by increasing the urea concentration in water/AOT/ -hexane microemulsions at/ = 10 [263],... 

The addition of water-soluble polymers, namely, polyoxyethylene glycol, polyacrylamide, and polyvinyl alcohol, to water/AOT/alcohol/decane w/o microemulsions decreases the intermicellar attractive interactions [190],... 

Percolation in microemulsions and concomitant microstructural changes are the focal points of this review. A complete understanding of percolation phenomena in reverse microemulsions will require an understanding of droplet interactions and the associated thermodynamics of droplet fusion, fission, aggregation to form clusters of varying fractal... 

In summary, a suitable association between dye molecules and the silica matrix is necessary for synthesis of DDSNs. Without the presence of chemical bonds or electronic interactions, the dye molecules will leak out from silica nanoparticles through the silica pores [22], Such DDSNs will provide unstable florescence signals and cannot be used as a labeling agent in bioanalysis. Meanwhile, water solubility is critical for a dye molecule when using a reverse microemulsion method to make the DDSNs. 

Organic molecules are solubilized by the organic constituents of a micelle. In small micelles the molecules lie close to the interface, while in large microemulsions considerable penetration into the core is observed (1.). Inorganic materials are quite polar and have little interaction with the organic components of the micelle. However, the micelle counterions,... 

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