Nano-structured and surface polymerized magnetorheological fluid

Magnetorheological polymer gels (MRPG), supramolecular magnetorheological polymer gels (SMRPG), and atom transfer radical polymerization (ATRP) magnetorheological fluid have been synthesized and characterized. Polyimide MRPG has high temperature resistance and is non-oxidizable. Supramolecular MRPG has good redispersion property. ATRP MRF has high stability and durability. Magnetorheological Polymer Gels (MRPG's) are composite fluids containing ferrous particles suspended in a polymer gel. In addition to modification of the carrier fluid, the polymer gel which includes crosslinked co-polyimide (CCPI) and solvent N-octyl-pyrrolidone, also changes the surface properties of the ferrous particles thus reducing the particle settling and improving particle redispersion. High thermally resistant CCPI is synthesized from dianhydride, diamine, diaminobenzonic acid and crosslinker and has a high glass transition temperature. The supramolecular network is obtained by metal coordination between terpyridine monomers and zinc ions. These SMRPGs have advantages such as controllable off state viscosity, reduced iron particle settling rate and improved stability. Viscoelastic behaviors of SMRPGs under small and large amplitude oscillatory shear are investigated using strain amplitude and frequency scanning mode. In order to improve the stability of MR fluid and reduce the friction between iron particles, surface initiated atom radical transfer polymerization (ATRP) approach is used to treat the surface of the iron particles. The surface reaction is characterized by FTIR and SEM. Molecular dynamics simulation is applied to study the thermal dynamic properties of carrier medium at molecule level. The miscibility of linear polyimide into N-octyl pyrrolidinone is simulated through NVT ensemble dynamics. The specific volume and thermal expansion coefficient (TEC) are simulated under the variation of temperature.