Reversible sacrificial hydrogen bonds enhanced ultra-high strength polybenzoxazine aerogel for thermal insulation.

[Display omitted] • A polybenzoxazine aerogel system with high strength under suitable deformation is designed. • Reversible sacrificial hydrogen bonding enhanced mechanical properties of the polybenzoxazine aerogel are realized. • The polybenzoxazine aerogel withstands more than 300,000 times its own weight under pressure before breaking. • The polybenzoxazine aerogel has a low thermal conductivity of 0.03012 W/(m·K) at 25 °C and 0.03486 W/(m·K) at 150 °C. • The polybenzoxazine aerogel has a hydrophobic angle of 148.7° and a saturated mass moisture absorption rate of about 0.63%. Aerogels are a very attractive class of lightweight and high-efficient thermal insulators, but poor mechanical properties have always been the main obstacle restricting their development and application. In order to overcome this problem, we innovatively used the concept of reversible sacrificial hydrogen bondings strengthening, and successfully synthesized a polybenzoxazine aerogel with outstanding mechanical properties and a lightweight structure. The aerogel (density 0.231 g/cm3 and porosity 90.7 %) exhibits a high compression strength of 14.36 MPa with a suitable deformation capacity of 19.6 % fracture strain, and also shows a relatively good fatigue resistance. In addition, the aerogel has outstanding thermal insulation properties [0.03012 W/(m·K) at 25℃ and 0.03486 W/(m·K) at 150℃] and hydrophobic properties (hydrophobic angle 148.7° and saturated mass moisture absorption rate about 0.63 %), thus it has great prospects for a high-efficiency thermal insulator used in buildings, industries, aerospace vehicles, etc. [ABSTRACT FROM AUTHOR]