Low-melting phthalonitrile thermosetting monomers with siloxane- and phosphate bridges

The series of low-melting siloxane- and phosphate-bridged phthalonitriles are studied. The monomers of this type possess glass transition temperatures more than 100 °C lower than for common phthalonitriles. Based on the collected experimental data molecular dynamics simulations aimed to predict glass-transition temperatures of the considered types of low-melting phthalonitriles are reported. The validity of computational model is confirmed by successful synthesis of the new monomers, e.g. phosphate- and phosphonate-bridged phthalonitriles are introduced for a first time. Cured Bis(3-(3,4-dicyanophenoxy)phenyl) phenyl phosphate demonstrates thermal performance featured to phthalonitriles (HDT ∼ 450 °C, T_5% = 524 °C, Y_c, (Ar) = 80%) along with increased thermo-oxidative stability. In aggregate with convenient processing the considered phthalonitriles can be used as high-temperature matrices for fiber-reinforced plastics production by vacuum infusion or RTM techniques.