Ionic-liquid-modified TiO2 spheres and their enhanced electrorheological responses

Abstract An ionic liquid functionalised silane agent, 1-(3-triethoxysilylpropyl)-3-methylimidazolium chloride (TESPM-IL), was prepared and used to fabricate ionic liquid (IL)-grafted titanium dioxide (IL-TiO2) spheres via a sol-gel process. Thermogravimetric analysis and Fourier transform infrared spectroscopy confirmed that TESPM-IL was attached to TiO2 spheres. Morphologies of the IL-TiO2 spheres were observed by scanning electron microscopy and transmission electron microscopy, indicating the rough surface and smaller size of the IL-TiO2 particles caused by the modification of TESPM-IL. The IL-TiO2 particles were applied as a new dispersed-phase material of electrorheological (ER) fluids. The ER effect of IL-TiO2 particles was studied and compared with that of pure TiO2 particles. It was found that, upon the introduction of TESPM-IL, both yield stress and storage modulus of the IL-TiO2 ER fluid were enhanced significantly, thus improving the ER effect of TiO2- or inorganic-based ER materials effectively. Dielectric analysis was also used to observe the interfacial polarization process of the particles, which confirmed the effect of the IL layer on the surface of the TiO2 particles.