Layer-by-Layer Assembly of Aerogel and Alginate toward Self-Extinguishing Flexible Polyurethane Foam

Flexible polyurethane foams (FPUFs) have wide applications in numerous fields; however, their high flammability seriously threatens the environment and humans. Thus, it is of practical significance to realize the self-extinguishing property of FPUF. Herein, silica aerogel and sodium alginate (SA) were deposited on the skeleton surface of FPUF utilizing electrostatic force through layer-by-layer assembly. The thermal, flameretardant, and smoke-suppression properties of coated FPUF were improved effectively. With increase in the number of coating layers, the coated FPUF has more significant flame retardancy. Compared with pure FPUF, the coated FPUF reaches V-0 rating during the vertical burning test, and PHRR and total smoke production (TSP) of coated FPUF were reduced by 69.41 and 78.11%, respectively. The improvements in flame-retardant and smoke-suppression properties of coated FPUF are attributed to the excellent protection barrier of the network formed by SA/silica aerogel, preventing the FPUF from further combustion from transferring into heat and toxic smoke gases.