A novel high-temperature naphthyl-based phthalonitrile polymer: Synthesis and properties

A novel naphthyl-based phthalonitrile monomer, 1,6-bis(3,4-dicyanophenoxy) naphthalene (1,6-BDCN), was prepared, and the phthalonitrile resin was cured with 4,4′-diaminodiphenyl ether (ODA) via two steps, namely, preparation of prepolymer and postcuring prepolymer at elevated temperatures. The 1,6-BDCN polymer might form triazine and phthalocyanine rings as demonstrated by FTIR spectra. The prepolymer shows fine solubility in organic solvents. The 1,6-BDCN polymer exhibits excellent structural integrity and superior thermal stability as indicated by thermogravimetric analysis (TGA). Dynamic mechanical analysis (DMA) revealed that the phthalonitrile resin has a high storage modulus and glass transition temperature (T_g). The water uptake is about 3% by weight after submersion in boiling water for 50 hours. The influence of curing processes on thermal stability and flame retardancy was also explored.