Dielectric properties of polystyrene-polypyrrole core-shell conducting spheres suspended in aqueous solution

The dielectric properties of polystyrene-polypyrrole (PS-PPy) core-shell conducting particles approximately defined as the uniform spheres in aqueous solution, were investigated in this work by dielectric relaxation spectroscopy (DRS) over a frequency range of 40 Hz to 110 MHz. One dielectric relaxation around 106 Hz was observed, which is ascribed to the interfacial polarization mechanism due to the accumulation of “counter-ions” on the boundaries of polypyrrole/solution. The relation between dielectric parameters and volume fractions of the particles shows the linear dependency in the range of investigation. Of interest to be noted, the permittivity of particles calculated from dielectric parameters on the basis of dielectric relaxation spectroscopy by using the Hanai method is much higher than 79.02 (εH2O=79.02,22°C). According to the present understanding of the interfacial polarization, the high permittivity of polystyrene-polypyrrole core-shell particles is mainly ascribed to the capture of counterions in polypyrrole matrix with porous morphology and the characteristic conducting mechanism of PPy itself. Moreover, the formation of many dipole moments between Cl− self-doped during the oxidative polymerization of pyrrole and N+ in the backbone of polypyrrole through the electrostatic interaction is also responsible for it.