Room Temperature Oxalic Acid‐Catalyzed, Ambient Pressure Dried, and Cost‐Effective Synthesis of Polybenzoxazine Aerogels for Thermal Insulation

The quest for ambient pressure dried, cost‐effective, and environmentally friendly synthesis technology has been continuously pursued throughout the aerogel research process. Herein, oxalic acid catalyst is used to synthesize a series of polybenzoxazine (PBZ) aerogels through room temperature ring‐opening polymerization and ambient pressure drying technique based on phenol‐4,4′‐diaminodiphenylmethane benzoxazine (PH–mda) monomer. The resultant PBZ aerogels with a microstructure of 3D nanoporous network exhibit a low density of 0.13–0.36 g cm⁻³ and relatively low thermal conductivities of 0.0323 (10⁵ Pa) and 0.0119 W m⁻¹ K⁻¹ (10 Pa), respectively. Remarkably, PBZ aerogels possess excellent compressibility (the maximum strain can be more than 80%), high compressive modulus, and specific modulus because of their rough skeleton structure. Taking advantage of the simple synthetic route, easily scaled‐up, lightweight, low thermal conductivity, and excellent mechanical property, such PBZ aerogels may have great potential to serve as a new material for energy‐efficient buildings and the other thermal insulating field.