Rapid preparation of Palygorskite/Al2O3 composite aerogels with superhydrophobicity, high-temperature thermal insulation and improved mechanical properties

Abstract

Al2O3 aerogels are widely employed in heat insulation and flame retardancy because of their unique combination of low thermal conductivity and exceptional high-temperature stability. However, the mechanical properties of Al2O3 aerogel are poor, and the preparation time is considerably long. In this study, we present a simple and scalable approach to construct monolithic Pal/Al2O3 composite aerogels using solvothermal treatment instead of traditional solvent replacement, which remarkably shortened the preparation time. Subsequently, to obtain stable superhydrophobicity (θ > 152°), the Pal/Al2O3 aerogel was modified by gas-phase modification method. The obtained Pal/Al2O3 composite aerogels demonstrate the integrated properties of low density (0.078–0.106 g/cm3), low thermal conductivity (1000 °C, 0.143 W/(m·K)), good mechanical properties (Young's modulus, 1.6 MPa), and good heat resistance. The monolithic Pal/Al2O3 composite aerogels with improved mechanical performance and improved thermal stability can show great potential in the field of thermal insulation.