A novel phosphorus–nitrogen-containing hardener toward anti-flammable, smoke-suppressed and low-dielectric epoxy thermosets

Abstract

The application of epoxy resins (EPs) in the new generation of electronic and electrical applications has been significantly hindered by their poor dielectric properties and flammability. To develop high-performance epoxy thermosets, a multifunctional phosphorus–nitrogen-containing curing agent (TFDP) was synthesized in this work via the reactions of 1-formylpiperazine (FPA), tris(2-aminoethyl)amine (TAEA), and dimethyl phosphonate (DMP). The epoxy thermosets prepared from the co-curing system composed of TFDP and diethyltoluenediamine (DETDA) presented remarkable advantages in terms of flame retardancy, mechanical properties, and dielectric properties. Specifically, EP-TFDP-2 presented a limiting oxygen index (LOI) value of 28 and achieved a UL-94 V-0 rating. ¹In addition, the EP-TFDP thermosets exhibit marked improvements in tensile strength and impact strength, with maximum increases of 51.5% and 67.4%, respectively. Importantly, the introduction of the TFDP effectively reduced the signal transmission loss of the epoxy thermosets. EP-TFDP thermosets exhibit lower dielectric constants and dielectric losses than unmodified EP thermosets. This strategy is highly significant for applications that require the simultaneous integration of lightweight, high-strength, low-dielectric, and highly flame-retardant EPs.