METHOD OF PRODUCING POLYETHYLSILOXANE-BASED FERROMAGNETIC LIQUID Russian patent published in 2014 - IPC H01F1/28 

FIELD: chemistry.

SUBSTANCE: disclosed is a method of producing a polyethylsiloxane-based ferromagnetic liquid, which involves precipitation of fine magnetite particles from aqueous solutions of ferrous and ferric salts with ammonia solution, stabilisation thereof with sebacic acid and peptisation in a mixed solvent which contains liquid polyethylsiloxane, a low-boiling hydrocarbon solvent and a fraction of alkyl derivatives of benzene or propylene oligomers which boil in the range of 250-400°C, in amount of 5-95% of the content of liquid polyethylsiloxane in the mixed solvent. The stabiliser is pre-dissolved in the low-boiling solvent, the low-boiling solvent used being ethanol and the liquid polyethylsiloxane used having a linear structure of general formula M₂D_n, where n=1-8, M - (C₂H₅)₃SiO_0.5, D - (C₂H₅)₂SiO, with number-average molecular weight of 1600-1750 g, density at 20°C of 0.99-1.00 g/cm³, viscosity at 20°C of 200-500 cS, thermal-oxidative breakdown temperature of 360°C. Stabilisation of the fine magnetite particles and peptisation thereof in a mixed solvent are carried out simultaneously while mixing and at a temperature of 80°C for 24 hours under a vacuum.

EFFECT: obtaining a polyethylsiloxane-based ferromagnetic liquid with high aggregative stability, stability in a magnetic field for long periods of time, with a wide operating temperature range and high saturation magnetisation.

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