Robust bamboo cellulose/phytic acid composite aerogels with thermal insulation, fire protection and acoustic absorption via ambient pressure drying

Abstract

Developing multifunctional cellulose aerogels (CAs) is important for reducing the ecological burden of plastic foams and achieving sustainable development across various fields. Ambient pressure drying is a promising technology for reducing production cycles, energy consumption and costs for aerogels. However, most CAs have poor flame-retardant and mechanical properties, and limited interfacial bonding leads to pore collapse and dimensional shrinkage under ambient pressure drying. Herein, bamboo fibers were used as a raw material to prepare multifunctional bamboo cellulose/phytic acid (BCPA) composite aerogels with robust strength via Schiff base reaction in cellulose aqueous dispersion, combined with freeze-molding and ambient pressure drying. The structural stability of BCPA aerogels is significantly enhanced by the synergistic effects of covalent and non-covalent interactions between the components, making them easy to prepare under ambient pressure drying. The BCPA aerogel with optimal performance exhibits low volume shrinkage (5.90%), low thermal conductivity (0.0333 W m⁻¹ K⁻¹) and high porosity (94.51%), while also possessing exceptional compressive strength (2.31 MPa at 80% strain), thermal insulation, flame retardancy and sound absorption properties. This work addresses the problems of porous structure shrinkage under ambient pressure drying and limited flame-retardant and mechanical properties of CAs, demonstrating process scalability and great potential in thermal protection, building energy conservation, and noise control.