BaTiO 3 -coated polyaniline core-shell nanocomposite particles for electrorheological fluids

Abstract

Novel electrorheological (ER) particles consisting of polyaniline (PAn) core and BaTiO₃ shell of different thickness were synthesized using an advanced method of combining controlled assembly with sol-gel process to integrate semi-conductivity of polyaniline and ferroelectricity of BaTiO₃. The PAn-BaTiO₃ core-shell nanocomposite particles were well characterized with TEM, XRD, FT-IR, XPS and TG-DTA. The electrical properties of the PAn-BaTiO₃ core-shell nanocomposite particles was tested and the ER behaviors of the ER fluids based on the PAn - BaTiO₃ particles with volume percent of 20 percent dispersed in chlorinated paraffin oil were investigated under DC electric field. The relationship between the ER activity and the electrical properties of the core-shell particles were discussed. The results showed that the PAn-BaTiO₃ shell-core nanocomposite particles with different shell thickness could be obtained by controlling the composition of sol solution and the coating times. There are chemical bonds between PAn core and BaTiO₃ shell, which are helpful for making them combined firmly. The ER effect of the PAn-BaTiO₃ core-shell nanocomposite particle was far stronger than that of pure polyaniline and barium titanate which were synthesized by the same method. For the PAn-BaTiO₃ core-shell nanocomposite, Both the BaTiO₃ shell thickness and polar groups of -OH existing on the surface of the particles have important influences on the ER effects.