Realizing balanced thermal safety and heat insulation in hydrophobic silica aerogel composites

Abstract

Interest in high-performance multifunctional hydrophobic silica aerogels (HSAs) has generated extensive discussion around HSAs endowed with enhanced infrared radiation suppression and excellent flame retardancy. Herein, we propose an eco-friendly and low-cost strategy for fabricating fire safe and infrared radiative shielding HSAs for sustainable thermal insulation. The as-created FRSA-BN-0.2 aerogel composite demonstrated superior flame retardant properties, with reductions in peak of heat release rate, total heat release, and total smoke release of 18.8 %, 36.1 %, and 88.8 %, respectively, compared to those of pure HSA. Additionally, the initial thermal degradation temperature and the temperature of peak heat flow were markedly increased by 95.0 °C and 104.1 °C, respectively. Furthermore, the aerogel composite exhibited outstanding hydrophobicity (a water contact angle of 142.1°), excellent thermal insulation (a thermal conductivity of 23.2 mW/m·K), and substantial infrared shielding performance. In this study, commercial flame retardant 9,10-dihydro-9-oxa-10-phosphophenanthrene-10-oxide (DOPO) was used as an acid catalyst substitute for strong acids, and boron nitride nanosheets were incorporated into the matrix to develop advanced multifunctional HSA aerogel composites. This material shows significant potential for application in fields such as aerospace, building insulation, and industrial thermal insulation.