Paper detail

Near field magnetostatics and Neel Brownian interactions mediated magnetorheological characteristics of highly stable nano ferrocolloids

Magnetic nanocolloids with synthesized super paramagnetic Fe3O4 nanoparticles (SPION) (5 to 15 nm) dispersed in insitu developed Polyethylene Glycol (PEG 400) and nano silica complex have been synthesized. The PEG nano Silica complex physically encapsulates the SPIONs, ensuring no phase separation under high magnetic fields (1.2 T). Exhaustive magnetorheological investigations have been performed to comprehend the structural behavior and response of the ferrocolloids. Remarkable stability and reversibility have been observed under magnetic field for concentrated systems. The results exhibit the impact of particle concentration, size and encapsulation efficiency on parameters such as shear viscosity, yield stress, viscoelastic moduli, magnetoviscous hysteresis etc. Analytical models to reveal the system mechanism and mathematically predict the magnetoviscosity and magneto yield stress has been theorized. The mechanistic approach based on near field magnetostatics and Neel Brownian interactivities can predict the colloidal properties under the effect of field accurately. The colloid exhibits amplified storage and loss moduli alongside highly augmented linear viscoelastic region under magnetic stimuli. The transition of the colloidal state from fluidic phase to soft condensed phase and its viscoelastic stimuli under the influence of magnetic field has been explained based on the mathematical analysis. The remarkable stability, magnetic properties and accurate physical models reveal good promise for the colloids in transient situations viz. magneto MEMS/ NEMS devices, antiseismic damping, biomedical invasive treatments etc.