Characterization and properties of metal phthalocyanine-Fe3O4 nanocomposites for electromagnetorheological fluids

Mese-scale metal phthalocyanine (MPc, M = Cu, Ni, Mn, or Co)-Fe3O4 nanocomp osites for EMR fluids have been prepared and well characterized. The result s indicate that there exists chemical bonding between MPc and Fe3O4 nanopar ticles, and their strength of chemical bonding increases in the following o rder: NiPc < CuPc < CoPc similar to MnPc. Compared to Fe3O4 nanoparticles, MPc-Fe3O4 nanocomposites have superior ability to anti-oxidation and therma l stability, and show almost the same saturation magnetic strength, but muc h less coercive force. All MPc-Fe3O4 nanocomposites have irregular spherica l shape with D of 0.2 similar to0.4 mum. The EMR fluids containing MPc-Fe3O 4 nanocomposites in chlorinated paraffin oil have excellent stability and r edispersibilty. They show reversible significant field-induced shear stress , which increase linearly with the increment of electric field strength (E) or H and which am different for MPcFe3O4 nanocomposites containing various metal elements, when E or H is applied respectively. Furthermore, field-in duced shear stress shows obvious synergetic effect when E and Il are applie d simultaneously.