Using Dicyclopentadiene-Derived Polyarylates as Epoxy Curing Agents To Achieve High Tg and Low Dielectric Epoxy Thermosets

To achieve high-T-g and low-dielectric epoxy thermosets, four dicyclopentadiene-derived polyarylates (26-P, 26-M, 236-P, and 236-M) were prepared from 2,6-dimethyl (or 2,3,6-trimethyl) phenol-dicyclopentadiene adduct with terephthaloyl (or isophthaloyl) chloride by high-temperature solution polymerization. The resulting polyarylates, exhibiting active ester linkages (Ph-O-(C=O)-) are found to be reactive toward a commercial dicyclopentadiene phenol epoxy (HP7200) in the presence of some lone-pair electron-containing compounds. Five compounds including 4-dimethylaminopyridine (DMAP), imidazole, 2-methylimidazole, triphenylphosphine, and triphenylimidazole have been evaluated as a catalyst for the curing reactions. We found that DMAP, with the smallest pK(b) among them, is the best catalyst according to differential scanning calorimetry, infrared, and thermal analyses. The thermal and dielectric properties of the polyarylate/HP7200 thermosets are evaluated. We found that they exhibit a high T-g characteristic (e.g., T-g is 238 degrees C for DMAP-catalyzed, 236-P/HP7200 thermoset). Furthermore, because of the hydrophobic methyl and cycloaliphatic moieties, and the secondary hydroxyl-free structure, polyarylate/HP7200 thermosets show a relative low-dielectric constant of around 2.75 U. The detailed structure-properties relationship is discussed in this work.