Study Of Polydiethylsiloxane-based Ferrofluid With Excellent Frost Resistance Property

摘要

The polydiethylsiloxane-based ferrofluid was prepared by dispersing finely divided magnetic Fe_3O_4 particles which are modified with oleoyl sarcosine and lauroyl sarcosine. The optimized experiment parameters including molar ratio of surfactant to Fe_3O_4 (1:5), temperature (80 ℃), stirring rate (300 RPM), the surfactant content of lauroyl sarcosine (0 to 33 mol%) and the modification time (25 min) were obtained by the orthogonal test. The magnetic liquid was characterized by a transmission electron microscope (TEM), infrared (IR) spectrometer, X-ray diffractometer (XRD), thermogravimetry (TG), vibrating sample magnetometer (VSM) and differential scanning calorimetry (DSC). It is indicated that the surfactant is mainly bonded to the surface of Fe_3O_4 nanoparticles through covalent bond between carboxylate (COO~-) and Fe atom. The modified magnetic particles are equally dispersed into the carrier and remain stable below -12 ℃ over 4 months. The ferrofluids exhibit excellent frost resistance property and distinctly reduced temperature coefficient of viscosity compared with polydimethylsilox-ane-based ferrofluids and hydrocarbon-based ferrofluids, respectively. The saturation magnetization could reach up to 27.7 emu/g.