Direct ink writing 3D printed graphene oxide nanocomposite aerogel for intelligent fire-warning and exceptional fire-shielding

Abstract

Fabricating intelligent fire-warning sensors with controllable 3D structures and shapes by advanced manufacturing technology is a formidable challenge but remains the critical factor in broadening fire prevention and protection. Herein, the novel fire-warning aerogel with a high-fidelity 3D porous structure and diversiform geometrical features based on graphene oxide (GO), cellulose nanofiber (CNF) and ammonium polyphosphate (APP) was fabricated via direct ink writing (DIW) 3D printing combined with freeze-drying technology. Benefiting from the hydrogen bonding multi-interactions between the molecules as well as the ideal rheological properties, the ink containing 20 wt% of CNF (GA-CNF-20) had a dynamic yield stress of 620 Pa. As a result, the corresponding aerogel had a significantly improved elasticity modulus of 153 kPa and a compressive stress of 400 kPa at a deformation of 39.7 %. Meanwhile, GA-CNF-20 displayed an ultrafast fire-warning trigger time (1.32 s) and a long-term response time (170 s) because of the thermal reduction property of GO together with the in-situ phosphorus doping reaction of APP under fire. Besides, the GA-CNF-20 also exhibited a strong heat-insulating capability, high char-forming property, self-extinguishing performance as well as structure integrity in the burning test. The relevant improvement mechanisms were attributed to the non-flammable gas diluting effect, intumescent char layer barrier effect and fire blowing-out effect in both gas and condensed phases. Such self-supporting printed aerogel can potentially be used as a fire-warning sensor for designated systems with specific precision structure in multi-domains of electrical and traffic engineering.