Phthalonitrile resin bearing cyanate ester groups: Synthesis and characterization

Abstract

Novolac resins bearing both cyanate and phthalonitrile groups in different proportions in the same backbone were synthesized and characterized. The resin was thermally cured to a network. Differential scanning calorimetric studies showed that cyanate and phthalonitrile groups underwent independent curing reactions. No evidence was obtained for co-curing of the two groups. Polymerization of cyanate groups preceded that of phthalonitrile groups and the former reaction was susceptible for catalysis. Incorporation of cyanate groups facilitated an early gelation of the resin and thus, the processability of the resin. However, this impaired marginally the moisture resistance and thermal stability of the otherwise inherently water resistant and thermally stable phthalonitrile resins.