Synthesis and characterization of phthalonitrile resins from <i>ortho</i> ‐linked aromatic and heterocyclic monomers

Abstract

Abstract This article describes the synthesis and properties of phthalonitrile polymers prepared from three different ortho ‐linked monomers, namely 2,2′‐bis(3,4‐dicyanophenoxy)biphenyl, 1,2‐bis(3,4‐dicyanophenoxy)benzene and 2,2′‐bis(3,4‐dicyanophenoxy)‐1,3,4‐oxadiazole. The resins exhibited a low complex viscosity, with a varying range of processing temperatures for all three systems. Thermogravimetric analysis showed that the synthesized polymers exhibited high thermal and thermo‐oxidative stability. The high char yields, which ranged from 64 to 69% at 900 °C under nitrogen atmosphere, and the high glass transition temperatures of the polymers indicated a high crosslinking density in the network structure. Dynamic mechanical measurements demonstrated that the fully cured monomer 2,2′‐bis(3,4‐dicyanophenoxy)‐1,3,4‐oxadiazole exhibited no change in glass transition temperature or in storage modulus up to 500 °C. © 2013 Society of Chemical Industry