Supramolecular magnetorheological polymer gels

Novel magnetorheological fluids-supramolecular magnetorheological polymer gels (SMRPGs)-were investigated. Supramolecular polymer deposited on the Surface of iron particles was suspended in the carrier fluids. The supramolecular network was obtained by metal coordination between terpyridine monomers and zinc ion. These SMRPGs had such advantages as controllable off-state viscosity, a reduced iron particle settling rate, and stability. The viscoelastic behavior of SMRPGs with small- and large-amplitude oscillatory shear was investigated using the amplitude and frequency sweep mode. The effects of strain amplitude, frequency, and magnetic field strength on the viscoelastic moduli were measured. The linear viscoelastic (LVE) strain range was obtained by the oscillation and static stress strain methods. The maximum LVE value was equal to the preyield strain point, 0.3%. Microstructural variation of SMRPG is proposed as an explanation of the rheological changes in the oscillation tests. The results of this research indicate that off-state viscosity and particle settling can be controlled by adjusting the concentration of supramolecular polymer gel. Dynamic yield stress significantly increased with an external magnetic field LIP to similar to 23,500 Pa under a magnetic flux density of 500 mT. (c) 2006 Wiley Periodicals, Inc.