Multifunctional waterborne polyurethane nanocoatings based on large-scale exfoliated mono-layered montmorillonite nanosheets

Ultrathin two-dimensional (2D) nanosheets have driven the development of multifunctional materials. However, persistent challenges with complex processes, low production rates, and high costs have prevented ultrathin 2D nanosheets from realizing their full potential in nanocomposite. Herein, large-scale exfoliated montmorillonite (MTM) mono-layered nanosheets in polyethyl-phosphate glycol ester were assembled into environment-friendly waterborne polyurethane to obtain multifunctional nanocoatings with superior matte performance, favorable flame retardancy, and high adhesion. Specifically, a significant 98.2 % decrease of 60° gloss from 65.0 GU to 1.2 GU was observed, which almost wholly diffuses incident light due to the rougher surface. Besides, total heat release and total smoke rate were decreased by a maximum of 27.1 % and 34.4 %, respectively. Surprisingly, the nanocoating with excellent anti-blocking properties has outstanding adhesion to PU leather. These nanocoatings on leather and fabric showed potential for engineering applications. This study may provide new insight for application of ultrathin 2D nanosheets in multifunctional materials.