Bamboo aerogel derived from waste bamboo flour for thermal insulation

• A three-step strategy to transform waste bamboo flour into a high-performance bamboo aerogel was proposed. • Bamboo aerogel demonstrates low thermal conductivity (0.036 W/m·K). • Bamboo aerogel demonstrates outstanding heat resistance (150℃). Development of green and renewable foams or aerogels from abundant biomass as an alternative for petroleum-based polymer foams is critical for resource and energy crisis. However, there exists strong intermolecular/intramolecular hydrogen bonding in cellulose chains and the composition of biomass is complex. Herein, we propose a three-step strategy to transform waste bamboo flour into a high-performance bamboo aerogel, including lignin and hemicellulose removal, ultrasonic treatment, and freeze-drying. As a result, the density of bamboo aerogel is as low as 0.031 g/cm 3 . The temperature at the maximum decomposition rate for bamboo aerogel was up to 338.7℃, which is 35℃ higher than that of bamboo flour. The obtained bamboo aerogel exhibits a refined porous structure composed of cellulose nanofiber network, endowing it with excellent flexibility and compressibility. Bamboo aerogel demonstrates an ultralow thermal conductivity (0.036 W/m·K), which is lower than those of biomass aerogels reported in literature. In addition, bamboo aerogel shows outstanding heat resistance (150℃), which outperforms the traditional polystyrene (PS), polypropylene (PP) and polyurethane (PU) foams. This work provides an effective method to develop high-performance biomass aerogels for fossil-based polymer foams substitution.