Fatigue resistant flexible silica aerogel for thermal sealing under force-heat coupling conditions

To develop a thermal insulation material to withstand force-heat environment changes, flexible silica aerogels (FSAs) were synthesized via in situ co-condensation of methyltrimethoxysilane (MTMS) and dimethyl dimethoxysilicone (DMDMS). The reversible deformation increased with DMDMS/MTMS volume ratio (D/M), resulting from the crosslinking degree of the Si-O-Si network. FSA with a D/M of 8:12 (FSA-3) exhibited a reversible deformation of 90% and maintained structural integrality under extreme loads. The flexibility of FSA-3 was extremely stable during long-term compression-release cycle up to 10000 times, and its hydrophobicity was maintained under high temperature up to 300°C. FSA-3 maintained insulation performance well under force-heat coupling conditions, exhibiting a decrease of 2.7-6.7% with a strain of 20-60%. This study offers significant guidance towards the development of silica aerogels for thermal sealing in aircrafts and electric vehicles.