Acidic phosphonium-based ionic liquid encapsulated on titania particles with enhanced electrorheological response

Abstract

Research on electrorheological (ER) fluids has led to significant advancements in the development of smart materials that adjust their viscosity in response to applied electric fields. This study focused on synthesizing titania ionogel-based particles (TiO2-IL) using an environmentally friendly sol-gel process involving tetrabutoxy-titanium (TBT) combined with an ionic liquid (IL), specifically 11-carboxyundecyl-triphenyl-phosphonium bromide. The successful incorporation of the IL into the TiO2 particles was confirmed through thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy and zeta potential analysis. The electrorheologial properties of TiO2-IL ionogel suspension in silicone oil were compared with those of pure TiO2 suspension. The addition of the ionic liquid (IL) significantly enhanced the electrorheological (ER) properties of the fluid, achieving a shear stress of approximately 1340Pa at an electric field strength of 5kV/mm. The fluid also exhibited excellent reversibility and a rapid response to changes in the electric field, which is attributed to the higher polarizability by the IL. Furthermore, the study observed low current density during operation, which helps maintain the fluid’s integrity and longevity under high electric fields. The fluids demonstrated stable ER effect across a temperature range of 40 to 70 ℃ and a reasonable sedimentation stability of around 80%. These characteristics, combined with the moderate conditions for particle preparation, make the TiO2-IL fluid a promising candidate for ER applications.