Fabrication and Shear Response of Conducting Polymer-Coated Zinc Ferrite Particles Under Magnetic/Electric Field

초록

A ZnFe2O4/poly(diphenylamine) (PDPA) particle with a core-shell structure was successfully synthesized with a ZnFe2O4 core via the solvothermal method, modifying ZnFe2O4 through a grafting agent and coating with a PDPA shell through the radical polymerization method. ZnFe2O4 is introduced as a new magnetorheological (MR) material because of its low density and sufficient saturation magnetization (M-s) value. PDPA does not require an additional de-doping process during electrorheological (ER) measurements because it has a lower electrical conductivity than typical conducting polymer of polyaniline. By measuring the morphology of the synthesized particles through transmission electron microscopy, it was confirmed that the core-shell structure was successfully synthesized and that the shell thickness of PDPA was approximately 14 nm. The density of the synthesized particles is 2.7 g/cm(3), which is sufficiently lower than the density of ZnFe2O4 (4.67 g/cm(3)), showing good sedimentation stability. The results from measuring the magnetic properties using a vibrating sample magnetometer indicate that the saturation magnetization value of ZnFe2O4/PDPA was approximately 40.8 emu/g. ZnFe2O4/PDPA particles were dispersed in 100 cs silicone oil by 5 vol.% to prepare a ZnFe2O4/PDPA-based electro/magnetorheological (EMR) fluid, and the shear response and dynamic response were measured using a rotational rheometer to measure the MR/ER properties.

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