Investigation of Mechanical and Thermal Properties of Graphene Oxide/ Octa(Aminophenyl) Polyhedral Oligomeric Silsesquioxane Hybrid Aerogels

In this paper, the mechanical properties, thermal conductivity, and thermal stability of graphene oxide/octa(aminophenyl) polyhedral oligomeric silsesquioxane hybrid aerogels with high porosity, high surface area, and ultra-low density were investigated. The combination of properties such as high surface area and porosity, and extremely low density and thermal conductivity have made these aerogels as a great candidate in a wide range of applications including energy storage and conversion devices (like supercapacitors, electrode materials etc.), contaminant absorbers, and thermal insulation. The mechanical properties and thermal stability of the prepared aerogels showed a significant improvement compared to the reported graphene aerogels. Investigation of the thermal conductivity results of the obtained aerogels showed that the contribution of heat transfer through the solid phase, λs, is superior to other heat transfer mechanisms. This superiority is maintained even at higher temperatures. This is attributed to the high self-extinction coefficient of graphene aerogels, which heat transfer through radiation is effectively suppressed. Likewise, the lower average pore size of the obtained aerogels, limits the mean free path of gas molecules at high temperature and thereby reduces the contribution of gas thermal conductivity. Since these aerogels have porosity of above 99.5%, the contribution of solid phase thermal conductivity was also very low. Finally, the influence of raw material content, density and morphology on mechanical properties, thermal stability, and thermal conductivity was investigated and the structure-properties relationship of the prepared aerogels was explained.