SYNTHESIS OF STRONTIUM TITANANTE/POLYANILINE NANOCOMPOSITES AND THE STUDY OF THEIR ELECTRORHEOLOGICAL EFFECT

摘要

The eletrorheological fluids (ERF), first reported by Winslow1 in 1949, consist of fine solid particles, dispersion medium and sometimes some additives. The original of the phenomenon has been explained as the polarization of fine particles in an isolating oil. Other researches focused on the mechanisms for the effect. According to the polarization theory, the more the difference of the dielectric constants between the dispersed particles and the dispersion medium, the higher the effect. So, high-dielectric-constant materials were preferred for the ERF. Perovskite type crystals(BrTiO_3 and SrTiO_3 et al) have been investigated as promising dispersed particles because of their high dielectric constants. However, the suspension stabilities were not as good as the organic particles because of their high densities. As organic dispersion particle, Polyaniline has been investigated for the ER effect under both DC and AC fields.10 This work provided a novel method to prepare Strontium Ttitanate/Polyaniline(STO/PANI) nanocomposites for the ER studies. Nanosized STO nanoerystals were synthesized by reverse microemulsion method. The nanocomposites were further prepared using the same microemulsion system. For convenience of further synthesis of nanocomposites, totally inorganic precursors were selected and a novel synthesis route was designed. Different from most of the previous works on STO synthesis, ultrapure nanoerystals were obtained without the final sintering process. This simple synthesis route ensured the preparation of final nanocomposites in an in situ manner and provided the whole synthesis an ultrapure micro-environment. With the analysis, the narto-STO-crystals showed a single crystal nature which provided a novel general method for the synthesis of other nanoerystals. The STO/PANI nanocomposites showed a novel embedded structure which can be applied not only in ER studies but also in nano-embedded capacitors. FTIR, XRD and TEM characterized the structure and morphology of the result particles. A field-loaded coaxial cylinder type rheometer was used for testing of the ER effect in silicone oil.