ABSTRACT
Abstract-The profound challenges of high-voltage pulsed-power applications make it imperative to design novel polymer dielectric materials for developing next generation high-energy density capacitor systems. Since the energy density has a quadratic dependence on the dielectric breakdown voltage (BDV) but varies only linearly with the dielectric constant, enhancement in the dielectric breakdown strength is considered critical to the performance of an electrostatic capacitor from an energy storage viewpoint. Based on the CVD diamond film paradigm as an outstanding high temperature capacitor with energy storage capability of 10 J/cm3, we developed a rationale for the design and dielectric evaluation of two classes of high-temperature polymer dielectrics by incorporating cycloaliphatic/diamondoid structural units in the backbone. One series of polymers comprised poly(aryletherketone triphenylphosphine oxide)s with cycloaliphatic/diamond-like hydrocarbon linking units. A novel series of high temperature cardo-polyesters containing trans-1,4-cyclohexane, 1,3-adamantane and 4,9-diamantane units were also specifically designed and synthesized for the dielectric study. The glass transition temperatures ranged from 330 to 400°C for the cardopolyesters with trans-1,4-cyclohexyl, 1,3-adamantyl and 4,9-diamantyl moieties. Tough, flexible and transparent thin films were solvent cast from these high-molecular-weight polymers. In the case of metallized polymer films fabricated from both the triphenylphosphine oxide series of polymers as well as the class of cardo-polyesters, the polymer film with the 4,9-diamantyl structural unit was found to exhibit the highest breakdown strength, as well as the highest calculated energy density for the dielectric. Findings in this study indicate the potential for enhanced energy storage capability in polymer dielectrics by the incorporation of even higher order diamondoids.
