Nanostructuring of 1-butyl-4-methylpyridinium chloride in ionic liquid–iron oxide nanofluids

Understanding the behavior of ionic liquids (ILs) in ionic liquid-based nanofluids has great significance for its proper application. The phase changes and solidification observed in most ILs offer a great challenge to nanoparticles stabilization. Herein, we have synthesized and characterized a new type of IL-based iron oxide nanofluids using 1-butyl-4-methylpyridinium chloride. We have investigated the formation of dendrite-like nanostructures by 1-butyl-4-methylpyridinium chloride at the IL–nanoparticle interface. This solidification induced under high electric field was nanoparticle size dependent and may be controlled by temperature and frequency changes. Examining the rheological behavior showed that higher volume fraction of nanoparticles in this nanofluids drastically decreased the flow viscosity causing a crossover from non-Newtonian (pure IL) to Newtonian and then to shear-thinning behavior. The nanofluid stability also decreased with the increase in nanoparticle size.