Novel vanillin-based benzoxazine containing phthalonitrile thermosetting system: Simple synthesis, autocatalytic polymerization and high thermomechanical properties

Benzoxazine containing phthalonitrile, as one of the most advanced high performance thermosetting resin, has gained a lot of attention in the last decades. Indeed, the combination of the thermally activated ring-opening polymerization of the benzoxazine and the cyano addition reaction of the phthalonitrile allows the development of robust polymeric networks. Following this path, a renewable natural resource, vanillin, was used to develop a new benzoxazine containing phthalonitrile thermosetting system. The newly developed monomers present the advantage of a simple synthesis process along with an autocatalytic polymerization mechanism. The molecular structures of the synthesized monomers were characterized by Fourier transform infrared spectroscopy and proton nuclear magnetic resonance spectroscopy . Thermal properties were also characterized by differential scanning calorimetry and thermogravimetric analysis . Typically, the newly developed monomers showed excellent thermal stability with starting decomposition temperatures over 496.4°C with a char yield at 800°C of about 80.7%. The thermomechanical properties were investigated by dynamic mechanical analyzer and the fractured surfaces were studied by scanning electron microscopy Globally, the newly developed partially bio polymer showed outstanding thermal resistance along with excellent thermomechanical properties.