Heat-Resistant Polymers From Bisaryloxy-Bisimido-Bisphthalonitriles Containing Dimethylsilane, Hexafluoroisopropylidene and Ether Linkages

Improved thermooxidative stable, high-temperature polymers that are processable into void-free composites were synthesized by thermal polymerization of three newly developed bisaryloxy-bisimido-bisphthalonitriles (BBBP) (I, II, and III) containing dimethylsilane, hexafluoroisopropylidene, and ether linkages, respectively. Thermal polymerization of BBBP (I, II, III, and IV) at 200-275 deg C for 2-10 h and postcuring at 310 deg C for 10 h gave tough, void-free, infusible, thermosetting polymers V, VI, VII, and VIII. thermal polymerization was monitored using infrared (IR) spectroscopy. Thermal polymerization of BBBP (I, II, and IV) was also carried out using cuprous chloride leading to the formation of polymers IX, X, and XI. The developed polymers were characterized by Fourier transform infrared (FT-IR), UV-visible spectroscopy and elemental analysis. The thermal stability of the polymers was evaluated using dynamic thermogravimetric analysis (TGA). Polymer V, VI, VII, and VIII exhibited onset of polymer decomposition temperature (PDT) at 499-503 deg C and are noteworthy for their high char yield of 67-71% in nitrogen at 800 deg C. Cuprous chloride polymerized polymers IX, X, and XI showed onset of polymer decomposition temperature (PDT) at 492-493 deg C and char yield in the range of 61-66% in N at 800 deg C. Polymers VII and VIII are potential candidates for preparing heat-resistant laminates and graphite composites for application in space, aerospace, and electronics industries.