Self-cured phthalonitrile resin via multistage polymerization mediated by allyl and benzoxazine functional groups

Self-curing allyl-functional phthalonitriles-containing benzoxazine (DABA-ph) has been designed and synthesized. These formed a resin through a curing process involving the sequential polymerization of allyl moieties, ring-opening polymerization of oxazine rings, and ring-forming polymerization of nitrile groups. The introduction of allyl moieties was found to improve the processability as the process started at a lower temperature of 160-200 degrees C than is needed for related resins. After self-curing, the resins exhibited high cross-linking degrees and excellent thermal stabilities. The glass transition temperature (T-g) was increased compared to similar resins to 380 degrees C with good thermal stability (5% weight loss temperature > 490 degrees C). These outstanding properties suggest the DABA-ph polymers are suitable candidates as matrices for high-performance composites.