Polyelectrolyte Photopolymer Complexes for Flame Retardant Wood

Wood is a widespread and renewable building material for both home and outdoor structures, but its flammability poses a safety concern in home structures and contributes to the propensity of outdoor structures to propagate wildfires. Existing methods of depositing polyelectrolyte treatments on wood are extremely time consuming and difficult to scale. Here, a polyelectrolyte complex is formed by the photopolymerization of an anionic phosphate-containing methacrylate in solution with cationic polyethylenimine. The resulting polyelectrolyte complex is the first such photopolymerized flame retardant coating to be reported in the literature. This coating imparts greater mechanical strength to the plywood at high temperatures with just 1.6 wt% added. Additionally, the coating reduces the plywood’s peak heat release rate in cone calorimetry testing and significantly decreases total smoke release. This scalable solution could enable more widespread adoption of polyelectrolyte-based technology and could make wood structures safer.