Low melting phthalonitrile resins containing methoxyl and/or allyl moieties: Synthesis, curing behavior, thermal and mechanical properties

Low melting phthalonitrile monomers containing allyl and/or methoxyl groups were designed, synthesized and characterized. In order to evaluate their potential application in phthalonitrile resins, these monomers were blended with 1,3-bis(3,4-dicyanophenoxy)benzene and 4-(4-aminophenoxy)phthalonitrile, then cured into polymers. Curing mechanisms of different prepolymers were proposed and compared, and processability, thermal and mechanical properties were characterized. The introduction of methoxyl units was found to postpone the curing, and thermal properties were slightly compromised. On the contrary, the usage of allyl was beneficial to both processability and thermal properties. More importantly, the impact strength for allyl-containing polymers could be as high as 13.63 kJ m−2, indicating such resin could be applied as high temperature structural composite matrices.