Molybdenum and tungsten disulfides surface-modified with a conducting polymer, polyaniline, for application in electrorheology

Molybdenum and tungsten sulfides are semiconducting materials with flake-like morphology. Their applicability in electrorheological suspensions was enabled by the coating with a conducting polymer, polyaniline, after its conversion to non-conducting polyaniline base. For instance, the conductivity of tungsten sulfide, 0.056Scm−1, increased to 0.98Scm−1 after coating with polyaniline, and was conveniently reduced to 6.3×10−6Scm−1 after conversion to polyaniline base. Such approach reduces the potential current drifts in electrorheological suspensions and allows for the application of sulfides in electrorheology. The optical microscopy demonstrated the formation of particle chains in silicone-oil suspensions after application of electric field. The electrorheological performance was assessed by the measurement of viscosity on the shear rate in the absence and in the presence of electric field and it is discussed on the bases of dielectric spectra.