Kevlar fiber-reinforced multifunctional superhydrophobic paper for oil-water separation and liquid transportation

In this study, the rational preparation of Kevlar fiber (KF)-reinforced eco-friendly paper based on ultralong hydroxyapatite nanowires (HAPNWs) is reported. The ultralong HAPNWs were used to constitute the paper skeleton, and KF was used to further enhance the mechanical properties of the paper. The KF and ultralong HAPNWs interweaved with each other to form a three-dimensional porous structure and immobilize TiO2 nanoparticles, resulting in high flexibility and mechanical strength of the paper; in particular, the writable paper exhibited superhydrophobic, anti-fouling, self-cleaning and oil/water separation properties after being modified with fluorine-free stearic acid (STA). Owing to the photo-induced hydrophilicity and photocatalysis of TiO2, the surface wettability could be tuned by UV light. Moreover, the as-prepared paper possessed promising thermal stability, and the weight percentage was maintained above 90% even when it was heated to 800 degrees C. Unlike traditional paper, the as-prepared paper manifested favorable fire-retardant properties even when it was directly exposed to fire for 5 minutes. Furthermore, the soft paper was utilized to efficiently separate an oil/water mixed solution; moreover, it was used to transport water and various organic liquids when lubricant oil was infused into the porous structure. The present study is propitious for the fabrication of multifunctional inorganic paper, which will find practical applications in the fields of paper making, liquid transportation, oil-water separation, fire-retardants, and waterproofing.