Doped dielectric polymers with low dielectric constant nanofillers

Nanoparticles, through interfacial effects, can markedly influence material properties of the matrix. Here we report the finding of a significantly enhanced dielectric response in dipolar polymers such as polytherimide (PEI) by doping with very low volume content nanoparticles. The presence of nanoparticles reduces the constraints on the dipole response to the applied electric field in the interfacial region, thus enhancing the dielectric constant. The finding eliminates the practical constraint of the traditional dielectric nanocomposites, where in order to raise the dielectric constant, inorganic particles with much higher dielectric constants are added to the polymer matrix, causing high local electric fields in the polymer and resulting in a large reduction of the electric breakdown strength. Our results demonstrate that through nanostructure engineering, the dielectric constant of polymers can be enhanced markedly without using high dielectric constant nanoparticles, thereby not compromising on breakdown strength.