Self-Curing Phthalonitrile Resin with Disulfide Bond as the Curing Group

To further investigate the presence of a radical mechanism in the curing process of phthalonitrile resins, a conventional radical initiation unit (disulfide segment) was introduced into phthalonitrile resins for the first time. A disulfide-bond-containing phthalonitrile monomer (DPBPN) was successfully synthesized. Its self-curing reaction could be promoted by disulfide segments in the precursor. Rheological measurements and differential scanning calorimetry showed that DPBPN exhibited a low melting point (124.5 °C) and a wide processing window (120 °C). Infrared spectroscopy confirmed the formation of isoindoline, triazine, and phthalocyanine structures in the product. Thermal gravimetric analysis and dynamic mechanical analysis suggested the outstanding thermal stability and high glass transition temperature (Tg) of the cured resin with a moderate curing process.