All-biomass phosphorylated cellulose/gelatin composite aerogel with excellent mechanical and flame-retardant properties

Biomass aerogel, with its renewable raw materials and excellent biodegradability, shows great potential for application in the field of green building insulation and heat insulation. However, its poor mechanical properties and inherent flammability severely limit its application in actual building scenarios. In this study, freeze-drying technology was employed to composite phosphorylated cellulose with gelatin. This preparation strategy regulates the mass ratio of phosphorylated cellulose to gelatin, leveraging the hydrogen bonding interactions between the hydroxyl and amino groups of their molecular chains to construct a “rigid skeleton-flexible connection” synergistic network structure, resulting in a fully biomass-based composite aerogel with excellent flame-retardant and mechanical properties, resulting in a fully biomass-based composite aerogel with excellent flame-retardant and mechanical properties. The “rigid-flexible” interaction between phosphorylated cellulose and gelatin endows the 3PM2G aerogel (The mass ratio is 3:2) with a low density (0.062 g/cm³) and a low thermal conductivity (0.047 W/m·K). Compared with phosphorylated cellulose aerogel without gelatin, the compressive modulus of 3PM2G aerogel was increased by 208 %. Phosphorylated cellulose and gelatin form a biomass intumescent flame-retardant system with a limiting oxygen index (LOI) as high as 73 % by providing carbon, acid, and gas sources. This study is expected to provide insights into the development of bio-based aerogels with high fire safety performance, thereby promoting green building and sustainable development.