Facile preparation of cellulose-SiO₂ composite aerogels with high SiO₂ contents using a LiBr aqueous solution

Cellulose-SiO₂ composite aerogels (CSGs) with high SiO₂ content up to 90% were successfully developed via the mixing of SiO₂ particles and a cellulose solution dissolved in a LiBr aqueous solution. The characteristic properties resulting from the direct gelation of a dissolved cellulose solution could facilitate the preparation of a variety of forms of SiO₂-embedded gels. The introduction of SiO₂ particles reduced the pore sizes while maintaining the three-dimensional porous structure of the regenerated cellulose matrix, resulting in increased density and decreased porosity. CSGs exhibited excellent mechanical properties, large surface areas, and thermal stability up to 250 °C in an air atmosphere. Furthermore, CSGs showed low thermal conductivity ranging from 0.038 to 0.048 W/m K despite the influence of higher density and lower porosity with increased SiO₂ contents. These results suggested that CSGs could provide a new option with regard to advanced porous organic-inorganic composite materials.