Nonfreeze-Drying Approach for Anisotropic Compression-Resilient Inorganic Aerogels by Guided Self-Assembly and Controlled Mineralization of Bacterial Cellulose

Increasing interest in aerogels among industrial sectors and the scientific community has sparked a sustained effort to develop methodologies for rational organization of aerogels for broader applications. Here we demonstrate that anisotropically compression-resilient cellulose/silica aerogels with tailorable macropores can be realized through guided self-assembly and controlled mineralization of bacterial cellulose. The cellulose/silica aerogels replicate the mesostructural features of modified bacterial cellulose with the macropores tailored during the biosynthesis using polystyrene spheres. Silica deposition surrounding bacterial cellulose nanofibers is controlled by moderating the hydrolysis and polycondensation of tetrapropoxysilane in the presence of cetyltrimethylammonium bromide. Cellulose/silica withstands 100 cycles with almost 100% height recovery along the growth direction and 1 cycle with 86.2% height recovery perpendicular to the growth direction at 60% compression strain. The anisotropic compression resilience is attributed to a multiscale deformation involving silica nanoparticles size, bead-on-string nanostructure, and oriented mesostructure of wavy fibers with cellular pores. The potential of the cellulose/silica aerogels for oily water cleansing is illustrated. Our work opens up new possibilities for bacterial cellulose-based advanced materials through in vivo mesostructure engineering and controlled mineralization.