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

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 over-come 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 light-weight 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 center dot K) at 25 degrees C and 0.03486 W/(m center dot K) at 150 degrees C] and hydrophobic properties (hydrophobic angle 148.7 degrees 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.