An efficient approach to prepare ether and amide-based self-catalyzed phthalonitrile resins

Phthalonitrile polymers with amide and ortho-, meta-, and para-substituted ether linkages in the backbone were synthesized successfully and their thermal properties were investigated. The monomer building blocks for these polymers were cured without the addition of catalysts due to the self-catalyzing nature of the monomer's amino group. The ether and amide functionalities in the chain enhanced their processability without compromising thermal stability. The resins exhibited a low complex viscosity over a wide processing window between the monomer melting temperature and the polymer cure temperature, with the processing temperature range varying significantly for para-, ortho-, and meta-substituted polymer architectures. All three systems exhibited high thermal and thermo-oxidative stability. The high char yields, which ranged from 66–75% at 900 °C under nitrogen atmosphere, and the high glass transition temperatures of the polymers indicate a high crosslinking density in the network structure.