An Environmentally Friendly Phosphorus-Modified Cellulose/Silica Hybrid Hydrogel for Fire Prevention and Firefighting

Wildfires have been recognized as a natural incident in some forests, however, fire season is now more severe and extensive, even in tropical rainforests in which fire could have damaging impacts. A hydrogel is a 3-D polymeric structure encompassing cross-linked and hydrophilic macromolecules. In comparison with water, hydrogels have shown some superiorities in terms of water-binding, cooling, and sealing, which make them be applied in forest fire prevention programs for improving fire-extinguishing performance. In this study, an environmentally friendly phosphorus-modified cellulose/silica hybrid hydrogel was prepared based on the modified methylcellulose by 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide–itaconic acid (DOPO-ITA) and silica nanoparticles. The storage (G') and loss (G") moduli increased with the increment of silica nanoparticles content, owing to the role of silica nanoparticles as crosslinking agent. In the fire prevention experiments, the grass treated with the methylcellulose@DOPO-ITA@silica hybrid hydrogel shows self-extinguishing behavior, whereas those treated with ordinary water or methylcellulose hydrogel can be easily ignited after one week. In the firefighting experiments, the methylcellulose@DOPO-ITA@silica hybrid hydrogel displays much shorter extinguishing time and lower consumption volume than ordinary water and the methylcellulose@DOPO-ITA hydrogel. This work presents an environmentally-friendly, non-toxic, and biodegradable cellulose-based hybrid hydrogel for fire prevention and firefighting of wildfires.