Compressible Magnetorheological Fluids (CMRFs)

A novel compressible magnetorheological fluids (CMRFs) has been prepared using iron particles (magnetic particles), silicone oil (carrier fluid) and microspheres (additives). The iron particles have been surface coated with poly(penta fluorostyrene) via reversible addition–fragmentation chain transfer (RAFT) . The polymer coating procedure includes 4 steps, which include benzyl 4-methoxydithiobenzoate as chain transfer agent (CTA); immobilization of surface initiator: 2-(4-chlorosulfonylphenyl)-ethyltrichlorosilane (CTCS) on the surface of iron particles; modification of surface initiated iron particles with CTA through atom transfer addition (ATA) reaction and graft polymerization of penta fluorostyrene on the surface of iron particles. Proton nuclear magnetic resonance (NMR) and matrix assisted laser desorption/ionization mass spectroscopy (MALDI-MS) are used to characterize the CTA. FTIR (Fourier Transform Infrared Spectroscopy), SEM (scanning electron microscope), DSC (differential scanning calorimeters) are used to characterize the surface coating on the iron particles. Controllable off-state viscosity and high shear yield stress can be obtained. Iron particles coated with polymer can considerably reduce the settling rate of iron particles and enhance stability of the magnetorheological fluid.