Experimental study on the effect of nanocellulose synergized with nanosilica on the stability of fluorine-free foam

Foam stability during the fire extinguishing process has always been a key factor limiting its efficiency and application. Previous studies have shown that adding a single type of nanoparticle to foam can improve stability to some extent. However, the foam stabilization mechanism research of multi-type particle synergistic surfactants is still not comprehensive. Therefore, this study explores the effect of nanocellulose (CNF) synergized with nanosilica (SiO₂) on the performance of 1227 cationic surfactant. The results show that in the 1227/SiO₂/CNF foam system, the negatively charged SiO₂ form a stable complex with the cationic head group of 1227 molecule, the hydrogen atom of the hydroxyl group of CNF can form a hydrogen bond with the nitrogen atom of the quaternary ammonium salt group of the 1227 molecule. Besides the electrostatic interactions between the negatively charged carboxyl functional group of CNF and the 1227 molecule, the high aspect ratio structure of CNF also enhances the dispersion of SiO₂ in the liquid film. 1227/SiO₂/CNF foam system in the optimal ratio has a maximum foam volume of 312 mL and a half-life of 3440 s, compared with the 1227 surfactant, the half-life can be increased by nearly 1000 %.