Crosslinking modification of poly(arylene ether nitriles) (PEN) based on the synergistic polymerization of aromatic methylene and mono‐cyano

Abstract In order to improve the heat‐resistance of poly(arylene ether nitriles) (PEN), a novel mono‐cyano crosslinking strategy—heat‐induced synergistic polymerization of aromatic methylene and mono‐cyano is proposed and applied in the PEN system. A self‐crosslinkable PEN containing aromatic methylene moieties (PEN‐F) is synthesized by a simple solution polycondensation. PEN‐F can significantly crosslink during relatively mild heat treatment at 300–325°C without any catalyst, transferring from thermoplastic polymers to thermosetting polymers. XRD, FTIR, TGA, DSC and DMA are applied to evaluate the crystallinity, structural evolution and thermal properties of PEN‐F before and after crosslinking. The results suggest that the uncured PEN‐F is amorphous and soluble in some common solvents (THF, DMAc, NMP, etc.). After curing, the heat and solvent resistance of PEN‐F improve remarkably. Especially, the resulting crosslinked product PEN‐F‐325 exhibits a high glass transition temperature ( T g ) value of 320°C measured by DMA, increased by 148°C compared to uncured PEN‐F ( T g = 172°C), potentially applicable for high temperature services.