Robust, Flame-Retardant, and Anti-Corrosive Waterborne Polyurethane Enabled by a PN Synergistic Flame-Retardant Containing Benzimidazole and Phosphinate Groups

Waterborne polyurethanes (WPUs) have attracted great interest owing to their environmentally friendly properties, and are wildly applied in production and daily life. However, waterborne polyurethanes are flammable. Up to now, the challenge remains to prepare WPUs with excellent flame resistance, high emulsion stability, and outstanding mechanical properties. Herein, a novel flame-retardant additive, 2-hydroxyethan-1-aminium (2-(1H-benzo[d]imidazol-2-yl)ethyl)(phenyl)phosphinate (BIEP-ETA) has been synthesized and applied to improve the flame resistance of WPUs, which has both phosphorus nitrogen synergistic effect and the ability to form hydrogen bonds with WPUs. The WPU blends (WPU/FRs) exhibited a positive fire-retardant effect in both the vapor and condensed phases, with significantly improved self-extinguishing performance and reduced heat release value. Interestingly, thanks to the good compatibility between BIEP-ETA and WPUs, WPU/FRs not only have higher emulsion stability, but also have better mechanical properties with synchronously improved tensile strength and toughness. Moreover, WPU/FRs also exhibit excellent potential as a corrosion-resistant coating.

Automated summary

Waterborne polyurethanes (WPUs) are environmentally friendly and widely used in production and daily life, but they are flammable. This study presents a novel flame-retardant additive, BIEP-ETA, which improves the flame resistance of WPUs by forming hydrogen bonds and phosphorus nitrogen synergistic effect. The WPU blends (WPU/FRs) showed improved fire-retardant effect, emulsion stability, mechanical properties, and corrosion resistance.