In situ co‐polymerization of high‐performance polybenzoxazine/silica aerogels for flame‐retardancy and thermal insulation

Abstract Materials with high‐performance thermal insulation and excellent flame‐resistance are incredibly desirable for energy conservation and fire safety. In this study, a novel hybrid nanostructure network polybenzoxazine/silica (PBO/SiO 2 ) aerogels were fabricated through facile in situ co‐polymerization sol‐gel methods with ambient pressure drying using benzoxazine (BO) monomers and SiO 2 sol as reaction source, N, N‐dimethylformamide (DMF) as the solvent and hydrochloric acid (HCl) as the catalyst. The hybrid nanostructure network was retained by polymerization–induced nanoscale phase separation of PBO and SiO 2 . The resulting PBO/SiO 2 aerogels exhibited finer microstructure, lower density (0.18 g/cm 3 ), thermal conductivity (0.031 W/m·K), and better flame‐resistance in comparison with PBO aerogels. They demonstrated an excellent compressive strength of 0.81 to 1.12 MPa at 10% deformation. The remarkable improvement in thermal insulation and flame‐resistance of PBO/SiO 2 aerogels could be attributed to the combined effects of finer microstructure and formation of SiO 2 that was “in‐situ” interpenetrated and interacted with silanols (Si‐OH) in the PBO network during the combustion process. The successful synthesis of PBO/SiO 2 aerogels highlights the possibility of fabricating a novel high‐performance thermal insulation and excellent flame‐resistance used for energy‐efficient buildings.