Ferrofluids ionic

Rgure 2.21. Force vs. distance profiles for ferrofluid emulsions stabilized with /3-casein at different concentrations (points). The ionic strength is 3 10 mol/1, pH = 6.2. The lines are the best fits (see the text for details). (Adapted from [78].)... 

Figure 2.22. (a) Disjoining pressure vs. thickness isotherm for an emulsion film stabilized by 0.1% BSA, ionic strength of 10 mol/1 NaCl, oil phase = hexadecane. The dots are the experimental data, dashed line is the double-layer contribution to the total disjoining pressure, and the solid line is the best fit done supposing additivity of the double-layer and steric forces, (b) Force vs. distance profiles for ferrofluid emulsions stabilized with mixed BSA-Tween-20 adsorption layers. The total concentration of the Tween-20 is kept constant = 5CMC, pH = 5.8. (Adopted from [78].)... 

Ferrofluids have recently been combined with other complex fluids to produce fluids with very interesting behavior. When ionic ferrofluids are doped into nematic liquid crystals (Brochard and de Gennes 1970), the resulting nematic liquid orients under a magnetic field 10 times lower than that required in the absenceof the dopant (Chen and Amer 1983 Bacri... 

Ferrofluids synthesized by chemical coprecipitation may be surfactant-stabilized ferrofluids or ionic ferrofluids. Surfactant ferrofluids are iron oxide nanoparticles coated by stabilizers or surfactant layer(s) for colloidal stability. The coating agents are polymers and surfactants, be they polar, non-polar or non-ionic. Fatty acid derivatives are most often used to stabilize these iron oxide nanoparticles either in organic or aqueous medium. If the particles are dispersed in an aqueous medium, a double layer of surfactant is needed to form a hydrophilic layer. On the other hand, if the particles are dispersed in an organic non-polar medium, one layer of surfactant forms a hydrophobic layer on the surface of the particles. 

Aksenov V, Avdeev MV, Bala oiu M, Bica D, Rosta L, Torok G, Vekas L Q Aggregation in non-ionic water-based ferrofluids by small-angle neutron scattering (to be published)... 

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