Synthesis and polymerization of disiloxane Si–O–Si-linked phthalonitrile monomer

A novel low melting highly hydrolytically stable phthalonitrile monomer containing Ar–Si–O–Si–Ar bonds with T_g = 4°C exhibits good rheological properties. Its cured resin possesses high heat deflection temperature (T_hd = 471°C) and demonstrates high thermal and thermooxidative stabilities (T_5% = 503°C, TOS_5% = 495°C, Y_c = 76%) that are typical of phthalonitrile matrices.