Polypyrrole–silica core–shell nanocomposites: a new route towards active materials in dielectrophoretic displays

A direct route to polypyrrole–silica core–shell nanoparticles with diameters in the 150–300 nm range is described to design new nanocomposites, in which the conducting part is wrapped by an external silica shell in order to obtain finally neutral conductive nanoparticles. The nanocomposites are characterized by SEM, FTIR, electrochemistry and thermal gravimetric analysis, demonstrating that the external silica shell actually insulates the conjugated polymer from the outer medium. In a second step, the nanocomposites are coated with an additional PDMS layer. The electrorheological properties of the ink made by dispersion of these final nanoparticles in a low dielectric constant fluid are checked in a dielectrophoretic device, in which the motion of the particles induced by an external electric field can be used to monitor a switch of the light transmission properties with a low voltage threshold.