Carboxylated cellulose nanofibers aerogels with enhanced flame retardancy and thermal insulation for intelligent fire warning systems

Developing intelligent fire alarm sensors with flame retardant and thermal insulation capabilities using advanced manufacturing techniques is a key challenge in enhancing fire coverage and protection. In this study, three-dimensional porous smart fire-warning aerogels were fabricated via a freeze-drying technique, using carboxylated cellulose nanofibers (CCNF), graphene oxide (GO), and sodium-based montmorillonite (Na-MMT) as the primary constituents, with boric acid (BA) serving as the cross-linking agent. The aerogel with 50 % CCNF (CCNF-GMB-50) not only exhibit low density and excellent thermal insulation properties but also maintain an ultra-long alarm duration of up to 300 s and a high sustained current of 74 mA even after the alarm is triggered, despite the continued burning of flames. Furthermore, the incorporation of GO and Na-MMT led to a 36.92 % reduction in average heat release rate (PHRR) and a 51.61 % decrease in peak CO 2 production rate (PCO 2 P), showcasing their synergistic effects. This study introduces a promising strategy for developing multifunctional materials that combine fire warning, flame retardant, and thermal management properties, with potential applications in building insulation, fire protection, and chemical safety. • The addition of a small amount of montmorillonite significantly enhanced the flame retardancy and thermal insulation of aerogels. • Aerogel can alarm continuously for 300 s under flame exposure. • The hydrogen bond composition of aerogels and the principle of flame retardant reinforcement were explored.