Electronic Transport Processes in Some Highly Insulating and Semi-Conducting Polymers.

Scope and method of study. In an effort to develop stable, highly polar, organic substances with dielectric qualities that can match or surpass those of BaTiO _3, a concentrated search effort among some one hundred fifty polymers of the polyacene quinone group was launched. The prospective candidate materials were studied for their dielectric constant and loss factor, activation energies and average molecular lengths (distribution), over a range of frequencies from 100 Hz-100 KHz (D.C.-100 KHz. for the electrical conductivity). Impedance bridge methods were employed to measure the various dielectric parameters and were supplemented by precision D.C. conductivity measurements. Techniques for carrying the measurements on these pre-pressed powdered polymers under ambient conditions of pressure and different temperatures, were developed and successfully tested for the first time. Findings and conclusions. Our investigations, based upon the existing theories and our own simplified model, showed that it is possible to achieve high-quality dielectric polymers provided certain monomer groups are used in the material synthesis, and provided other factors related to the phonon frequency of the lattice are enhanced. Specifically, the effect of the D.C. conductivity on the dielectric loss was found to be nil, suggesting that the A.C. and the D.C. conduction mechanisms are mediated by different types of charge carriers. The experimental results were in very good agreement with our own derived model, as well as with the results of other researchers in this field of (PAQR) polymers.