An eco-friendly and facile method to prepare waterborne polyurethane based fire-resistant & waterproof coatings for wood protection

The fire-resistant & waterproof coatings for wood protection are highly demanded to reduce fire risk and save lives because wooden furniture and in-house decorations are widely used in our daily life. Herein, an eco-friendly and facile method was proposed to prepare such coatings, where a waterborne polyurethane (WPU) with non-volatility was blended with commercial flame retardants. A coating of ∼250 μm could generate charcoal of ∼10 mm that the painted plywood could withstand burning for ∼20 min. For the purpose to turn the hydrophilic WPU into water-repellent coating, hydrophobic nano-SiO2 were sprayed onto the surface to assemble into hierarchical structure. Consequently, the coating showed strong water repellency and the water contact angle arose from ∼89° to ∼157°. This method is conducive to the industrial production of fire-resistant and waterproof coatings due to its green and easy-to-scale up features, which will benefit thousands of households.