The samples of magnetic liquid stabilized by a double layer of surfactant in water using non-ionogenic stabilizer TWEEN 20 (Polysorbate 20) as the second layer were synthesized. The rheological properties of the synthesized samples depending on their concentration were investigated. In contrast to liquids with dissociated surfactant, the viscosity of the magnetic liquid decreases faster with temperature increase than the viscosity of the base medium (water). The main advantage of using non-ionogenic surfactant is the possibility of synthesizing low-temperature magnetic liquids based on water-alcohol mixtures and aqueous salt solutions. Fluids stabilized by TWEEN 20 in ethylene glycol and propylene glycol solutions retain mobility up to temperatures –40°C and –50°C. When calcium chloride CaCl solution was used as a base medium, the test sample of the fluid retained performance up to temperature –30°C. Magnetic liquids based on alcohol and salt solutions can be indispensable in the fields of engineering, where strict requirements are made to their fire and environmental safety. Chemical passivity of particles stabilized by TWEEN 20 makes their application in biology and medicine possible.
Lebedev et al. (Wed,) studied this question.