Preparation of Cellulose/CL-20 Composite Energetic Aerogels by Crystal Growth of CL-20 in Cellulose Solution

Hexanitrohexaazaisowurtzitane (CL-20) is one of the most powerful high-energy explosives, used in the form of composite explosives due to its high mechanical sensitivity and the presence of crystal defects. Cellulose is widely known for its excellent compatibility and loading capacity as a green natural polymer. In this paper, cellulose/CL-20 composite energetic aerogels (CCAs) were developed by using cellulose as a carrier for CL-20 particles and 1-allyl-3-methylimidazolium chloride (AMIMCl) as a cosolvent for cellulose and CL-20. The crystal growth regularity of CL-20 was studied in the process of cellulose regeneration. The results show that CCAs maintain a 3D network structure where CL-20 crystals grow and adhere along the extension direction of the cellulose fibers. More specifically, cellulose fibers form a dense membrane structure on the surface of CL-20 crystals and CCAs with a coverage degree of 89.48%. The loading of CL-20 in CCAs is as high as 94.4%, and the crystal form remains unchanged. The thermal stability, impact sensitivity, and friction sensitivity properties of CCAs greatly improved in comparison with raw CL-20 due to the protection provided by the cellulose membrane and the formation of new chemical bonds between CL-20 and cellulose.