Enhanced electrokinetic,dielectric and electrorheological properties of covalently bonded nanosphere-TiO2/polypyrrole nanocomposite

Nanosphere-TiO₂ was synthesized, surface functionalized with (3-aminopropyl) triethoxysilane (APTS) and then covalently bonded with polypyrrole (PPy) with bottom-up surface engineering strategy to obtain nanosphere-TiO₂/PPy core/shell hybrit nanocomposite. All the materials were subjected to full chemical and morphological characterizations by using various techniques. The presence of NaCl, AlCl₃, cetyltrimethyl ammonium bromide and sodium dodecylsulfate observed to cause high colloidal stabilities of the nanocomposite dispersions by reaching to zeta(ζ)-potential values of ζ > + 30 mV and ζ < ? 30 mV. A series of suspensions were prepared by dispersing nanosphere-TiO₂ and nanosphere-TiO₂/PPy particles in insulating silicone oil (SO) and dielectric properties were determined using an LCR meter. Antisedimentation stabilities of these suspensions were determined against gravitational forces and 54% colloidal stability was achieved with the nanocomposite after 30 days. Polarizabilities of the suspended particles were observed using an optical microscope under externally applied electric field strength. Then the suspensions were subjected to electrorheological measurements by investigating the effects of shear rate, particle volume fraction, shear stress, and electric field strength. Non-Newtonian shear thinning behaviors were observed for the samples. Further, vibration damping characteristics of the materials were determined with shear stress and frequency oscillation measurements. Enhanced reversible viscoelastic deformations were observed for the dispersions from creep-recovery tests and 64% creep-recovery was obtained for nanosphere-TiO₂/PPy/SO system under E = 3.5 kV/mm.