Facile Synthesis of Mechanical Elastic, Hydrophobic, and Thermal Insulation Silicon Composite Aerogel Enhanced by Phosphorylated Cellulose Nanofibril

ABSTRACT As advanced thermal insulators, silicon‐based composite aerogels are promising materials in various fields of application, ranging from aerospace to transportation. However, the complex fabrication process of aerogel materials at room temperature is challenging, thereby restricting their practical application. In this work, a lightweight and mechanically elastic silicon‐based aerogel (DMF‐P) enhanced by phosphorylated cellulose nanofibrils was successfully fabricated via an ambient‐pressure drying method. The resultant aerogel showed excellent mechanical performance, that is, high compressive strength of 222 kPa at 80% strain, while retaining 90% after 100 loading cycles. This enhancement can be attributed to the enhanced hydrogen bonds formed between phosphorylated cellulose nanofibrils and the siloxane matrix. In addition, DMF‐P aerogel possesses good hydrophobic performance and oil–water separation capability, as evident from its high water contact angle (144.7°) and excellent adsorption capacity (15 g/g) for oil‐based solvents. Notably, the DMF‐P aerogel exhibits exceptional thermal insulation capability, maintaining an insulation temperature exceeding 200°C under harsh thermal conditions at 300°C after a sustained period of 15 min. The strategy proposed herein provides an alternative path to achieve high‐performance aerogel materials, offering a promising candidate for applications demanding both mechanics and thermal insulation.