Biobased Diglycidyl Ether Diphenolate Esters for Structural Capacitor Applications

Structural Capacitors make use of multifaceted materials as dielectrics that serve a dual purpose, one of structural integrity through physical-mechanical properties and the other as a highly capable storage of energy. To meet the needs that structural capacitor applications demand and broaden the library of available dielectric materials, thermoset diglycidyl ether of diphenolate esters (DGEDP) were explored. DGEDP exhibits comparable mechanical properties as those of diglycidyl ether of bisphenol A (DGEBA), while being derived from levulinic acid, a safe and readily renewable feedstock, which cannot be said for the pertroleum derived DGEBA. A series of DGEDP-esters (i.e. methyl, ethyl, propyl, butyl, allyl, and benzyl esters) were synthesized and studied in order to determine whether DGEDP esters were a potential replacement for DGEBA in structural applications. Broadband dielectric spectroscopy revealed that DGEDP-propyl had the highest dielectric constant out of the DGEDP-n-alkyl ester series and DGEBA, while also displaying similar mechanical properties. The differences in the dielectric properties of the DGEDP-n -alkyl esters were attributed to the interplay of increasing ester chain length, increasing conformational and localized motions, steric hindrance and free volume.