Preparation of DOPO-KH550 modified hollow glass microspheres/PVA composite aerogel for thermal insulation and flame retardancy

The creation of high-performance thermal insulation and flame-retardant materials is of great importance for minimizing energy consumption and reducing fire risk for modern buildings. Herein, we report the creation of a new composite aerogel, which was prepared by incorporation of 9,10-Dihydro-9-oxa-10-phosphaphenanthrene 10-Oxide-3-Aminopropyl triethoxysilane (DOPO-KH550) modified hollow glass microspheres (HGM) into polyvinyl alcohol (PVA) using citric acid as a cross-linker, as a kind of thermal insulation and flame retardant materials (abbreviated as PVA-DKHGM). The as-synthesized PVA-DKHGM composite exhibits superior thermal conductivity of 0.0187 W m-1 K-1, owing to the hollow structure of the hollow glass microspheres and rich porosity. Besides, it reaches V-0 level at the UL-94 test and the peak heat release rate (pHRR) was measured to be 114.93 (kW/m2) which is lower than most composites now. These results are attributed to the synergy effect of the hollow glass microsphere and DOPO-KH550 which offers the composites aerogel excellent flame retardancy. Owing to its advantages such as lightweight, highly porous, thermally stable, simple to prepare, high mechanical strength, and can be further scaled up, our PVA-DKHGM aerogel may hold great potential for practical applications in construction of energy-saving modern buildings.