Nanopore Construction and Anti-Oxidation/Ablation Resistance Mechanism of POSS-Hybrid Phenolics

In response to the stringent requirements for lightweight and high-performance materials in the field of aerospace ablative thermal protection, phenolic aerogels, despite their advantage of low density, have insufficient thermal insulation and ablation resistance to meet the service demands in extreme environments. In this study, POSS-modified phenolic aerogels were prepared via the ring-opening grafting reaction between polyhedral oligomeric silsesquioxane (POSS) and phenolic resin, combined with the sol–gel method. The resulting aerogels exhibit a specific surface area of 103.9 m 2 /g and the temperature at the maximum weight loss rate up to 843.85 K. Additionally, the thermal conductivity of P-E-10 decreases from 0.119 W/(m·K) to 0.091 W/(m·K). Their excellent thermal insulation performance was verified through a self-designed thermal insulation experiment and COMSOL simulation. Under the ablation of a butane torch flame with a heat flux of approximately 100 kW/m 2 and a central temperature of approximately 1373.15 K, the material demonstrates efficient ablation resistance, with a linear ablation rate as low as 7.75 μm/s. In conclusion, POSS-modified phenolic aerogels exhibit broad application prospects with high competitiveness in the field of ablative thermal protection in the future.