Construction of HLNPs/Fe3O4 based superhydrophobic coating with excellent abrasion resistance, UV resistance, flame retardation and oil absorbency

Superhydrophobic coatings are suffering from low mechanical strength, poor stability, easy aging, and insufficient environmental performance, etc., limiting their further application. In addition, developing multifunctional superhydrophobic coatings is a trend. To improve the above problems, the biomass particles (hydrothermal treated lignin nanoparticles (HLNPs)/Fe3O4) were prepared by solvent displacement and hydrothermal reaction and used as the main materials, both nanocellulose crystals (CNC) and TiO2 as the reinforcers, PDMS as the adhesive to prepare the HLNPs/Fe3O4 based magnetic and superhydrophobic coating only by one-step spray or dip. The resulted wood had the water contact angle (WCA) of 167° and the slide angle (SA) of 5° and showed excellent abrasion resistance and outstanding ultraviolet (UV) resistance. It could resist 87 abrasion cycles due to the synergistic enhancement of both CNC and TiO2 and withstood ultra-high UV (1000 W) radiation of 9 h due to the strong UV absorption of lignin molecules. And the resulted polyurethane (PU) sponge demonstrated highly effective oil absorbency with the absorption efficiency of 17.17-24.78 g/g for four different oils and could be recovered using a magnet. Besides, under the combined effect of inorganic particles and lignin, the superhydrophobic and magnetic PU sponge displayed outstanding flame retardation and the limited oxygen index (LOI) value reached 27.3%. This study would help promote the development and improvement of [email protected] composite superhydrophobic coatings and provide a new way for the high-value utilization of lignin.