Octanoic acid as a novel solvent for low electric field electrorheological fluids

This work highlights the peculiar electrorheological (ER) effect shown by suspensions of TiO2 nanoparticles (~ 5 nm) in octanoic acid. Such suspensions show a marked increase in viscosity already at very low applied fields (~ 400 V/mm). This has been attributed to the octanoic acid chemical nature and in particular to its fluidity and its capability to establish interactions with the TiO2 nanoparticle surface. The study was performed as a function of nanoparticle volume fraction (?) in the range 3-10% and surprisingly no scaling with ? of the ER performance was observed. The low cost of materials involved, the simplicity of fluid preparation, and the ER response already at unusually low electric fields constitute important factors which deserve to be tailored for large scale and mass application.