Facile fabrication of highly flame-retardant superhydrophobic coatings on kraft paper via a simple and efficient method

To solve the problem of poor water resistance and flammability of kraft paper, we proposed a simple and efficient method for preparing highly flame-retardant superhydrophobic coating for kraft paper. Ammonium polyphosphate (APP) and aluminum hydroxide (ATH) were utilized as the flame retardant layer, while Polydimethylsiloxane (PDMS) and candle soot were employed for the superhydrophobic layer. The results revealed that the limiting oxygen index (LOI) of superhydrophobic flame retardant kraft paper (SFKP) was as high as 80%, 296.0% higher than that of ordinary kraft paper (OKP). In addition, the water contact angle (WCA) of the SFKP surface reaches 154.1°, and the water sliding angle (WSA) is 3°. Meanwhile, the WCA of SFKP remains above 150° after 12 h of immersion in water. This indicates that SFKP has excellent flame retardancy and water resistance, and is expected to be utilized in harsh environments such as floods or fires.