Enhanced Electroresponsive Performance of Double-Shell SiO2/TiO2 Hollow Nanoparticles.

The double-shell SiO2/TiO2 hollow nanoparticles (DS HNPs) are successfully fabricated and adopted as dispersing materials for electrorheological (ER) fluids to investigate an influence of shell structure on ER properties. The DS HNPs-based ER fluid exhibits outstanding ER performance which is 4.1-fold higher compared to that of single shell SiO2/TiO2 hollow nanoparticles (SS HNPs)-based ER fluid. The significantly improved ER property of DS HNPs-based ER fluid is ascribed to the enhanced interfacial polarization. In addition, the ER activities of DS HNPs-based ER fluids are examined depending on the particle diameter. The yield stress of DS HNPs-based ER fluids increases up to 302.4 kPa under an electric field of 3 kV mm(-1) by reducing the particle size, which is remarkable performance enough to promise sufficient probability for practical and industrial applications. The enhanced ER performance of the smaller DS HNPs is attributed to the increased surface area of large pores (30-35 nm) within the shells, resulting in a large achievable polarizability determined by dielectric constants. Furthermore, the antisedimentation property is analyzed in order to offer an additional insight into the effect of particle size on the ER fluids.