Multifunctional phthalonitrile aerogel composites: preparation, performance and potential

The design and synthesis of porous materials represent a critical strategy for advancing multifunctional applications of phthalonitrile resins. By coupling the intrinsic thermomechanical stability derived from heterocyclic macromolecular architectures with the functional benefits imparted by micro- and nanoporous structures, these materials offer enhanced high-performance options to meet demanding service conditions. Herein, we present a novel multi-step methodology for fabricating nanoporous phthalonitrile aerogel composites (PNAC), comprising phthalonitrile solution formulation, fiber reinforcement impregnation, sol-gel reaction, ambient-pressure drying, and post-curing. The resulting aerogel matrix features a three-dimensional porous skeleton composed of interconnected nanoparticles. Thermal analysis reveals exceptional stability, with a 5 % weight loss temperature (T_d5) of 466 °C and a char yield of 55 wt% at 1000 °C. Incorporation of needled quartz fiber felt significantly improves the dimensional stability during processing. The prepared PNAC demonstrates a unique combination of properties: low density (0.28 g cm³), ultralow thermal conductivity (54.3 mW·m⁻¹·K⁻¹ at 25 °C; 58.7 mW·m⁻¹·K⁻¹ at 200 °C), pronounced hydrophobicity (static contact angle: 141°), and self-extinguishing behavior. This multifunctional profile positions PNAC as a promising candidate for extreme-environmental applications.