One component propargyl phthalonitrile novolac: Synthesis and characterization

• First time report on one component propargyl–phthalonitrile thermosets.
• Propargyl mediated nitrile curing is established in an oligomer system.
• Phthalocyanine, triazine, and chromene structures are identified in cured resin.
• Compositional dependency on thermal stability and crosslinking established.

Novolac polymers bearing varying proportions of propargyl and phthalonitrile groups on the same backbone and capable of self and co-curing to a thermally stable matrix have been synthesized. Spectral and thermal studies gave evidence for both homopolymerization of propargyl groups and its co-reaction with nitrile groups during thermal curing. Propargyl groups promoted curing of phthalonitrile groups through the hydroxyl and chromene intermediates formed from the thermal cyclization reactions of this group. Resins rich in propargyl groups showed higher crosslink density and higher modulus values. Among the copolymers, phthalonitrile rich systems exhibited relatively higher thermal stability with initial decomposition temperature at around 435 °C. All the cured compositions showed anaerobic char yields of 73–76% at 900 °C.

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