Fabrication and properties research on a novel perfluoropolyether based ferrofluid

Abstract

Abstract Conventional ferrofluids are not satisfactory in special fields, especially in corrosive and extreme temperature conditions. In this study, perfluoropolyether based ferrofluid with outstanding performance was synthesized by high energy ball milling. The results of XRD, TEM and particle size analyzer show that the modified Fe3O4 is well crystallized, globular shaped and monodisperse. Magnetic particles in a narrow size distribution ranging from 8 nm to 15 nm and the average is approximately 10 nm. Characteristic peaks in FT-IR and XPS spectrum confirm that Fe3O4 MNPs are successfully decorated by perfluoropolyether carboxylic acid surfactant. Perfluoropolyether based ferrofluid exhibits superparamagnetism, and magnetization is 22.83 emu/g at 10 kOe. Surface tension of perfluoropolyether based ferrofluid is 25.18 mN/m at 25 °C; Viscosity decreases with temperature increasing, which can be fitted as I· = e a+bT+c T 2 . In heating progress from −20 °C to 25 °C, perfluoropolyether based ferrofluid is a non-Newtonian fluid, while from 25 °C to 100 °C, it is a Newtonian fluid with almost constant viscosity. Viscosity of perfluoropolyether based ferrofluid increases to 1825.7 mPa·s at −20 °C and is still flowing at −40 °C. Yield point occurs when deformation reaches to 10%, and increases along with electromagnetic field in magnetic rheological behavior.