Research in dielectric materials is proving to be increasingly significant as the world shifts its focus towards electrical energy. High energy density capacitors have established their importance in applications consisting of hybrid electric vehicles and insulators. Through the combination of density functional theory (DFT) and experimental design, polymers have been prepared and studied for their dielectric constant and band gap capabilities. Through this rational co-design process, certain polyureas were identified as having promising electrical properties. Specifically, free-standing polymeric films consisting of the polyureas toluene diisocyanate- JEFFAMINE®, EDR-148 polyetheramine (TDI-EDR148) and methylene diphenyl diisocyanate- JEFFAMINE®, EDR-148 polyetheramine (MDI-EDR148) have been synthesized. These isocyanates reacted with the ether-containing JEFFAMINE®, EDR-148 polyetheramine, to form polyureas with molecular weights reaching up to 100,000 g/mol. This relatively high molecular weight for a condensation polymerization allowed quality films to be made of these polyureas at differing concentrations and through different casting techniques. The resulting TDI-EDR148 and MDI-EDR148 polyureas exhibited relatively high degradation and glass transition temperatures (Tg). A dielectric constant value of around 4.5 was obtained from the TDI-EDR148 film while maintaining a loss below 2%. The film also exhibited an energy density greater than 10 J/cm3 and a breakdown strength greater than 600 kV/mm. These new polymers show promise for future thin film capacitors and might compete with the current industry standard biaxially oriented polypropylene (BOPP) which has a dielectric constant of 2.2 and breakdown of 730 MV/m, resulting in a maximum theoretical energy density of 5 J/cm3.

Polyureas for dielectric applications developed through a rational co-design approach

253rd National Meeting (2017)

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