Enhanced thermal property via tunable bisphenol moieties in branched phthalonitrile thermoset

The development of high-temperature resistant polymers and their composites is of particular interest because of their ever-growing applications. Herein, a family of branched phthalonitrile resins based on different bisphenols (Hydroquinone, 4,4′-Biphenol, m -Dihydroxybenzene, 1,6-Dihydroxynaphthalene, 2,6-Dihydroxynaphthalene) and phenyl- s -triazine, endcapping with 4-nitrophthalonitrile were prepared via a convenient condensation polymerization procedure. The relationship among bisphenol structures, thermal properties and mechanical properties were investigated in details. By incorporating the thermally stable phenyl- s -triazine segment into the branched phthalonitrile's backbone, the overall T g (glass transition temperature) and T d (5% thermal degradation temperature) of the derived polymers were significantly improved. The resins were thermally cured to networks with 4,4′-diaminodiphenyl sulfone (DDS) as curing agent . The resulting networks exhibited high thermal resistance , indicated by T g surpassing 500 °C and T d as high as 575 °C. Additionally, the composites exhibited high mechanical properties and dielectric properties stability at 500 °C. The results suggested the merits of branched phthalonitrile polymers for applications in high-temperature resistant polymers and composites.