Inspiration from a new lignin-derived phthalonitrile resin: Unique curing behavior, and thermal properties

Abstract In this paper, a novel lignin-based phthalonitrile monomer (BPN) was synthesized with a biomass content of 54%. Its structure was confirmed by infrared spectroscopy (IR), 1H NMR spectroscopy and elemental analysis. The curing behavior of BPN was studied by rheological analysis. The thermal polymerization mechanism was discussed by bisphenol A based phthalonitrile (BAPh) control experiment, in situ IR and solid-state 13C NMR. We proposed the curing mechanism of “methyne-activated phthalonitrile thermal polymerization”. The thermomechanical and thermal properties of the cured product were characterized by dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA), respectively. The results show that the cured BPN has a comparable glass transition temperature (Tg = 400 °C) and better thermal stability than petroleum-based BAPh. On the other hand, compared with previous bio-based phthalonitrile resins, the cured BPN exhibits comparable or superior thermal properties and a higher biomass content.