Facile preparation of economical, eco-friendly superhydrophobic surface on paper substrate with excellent mechanical durability

In this paper, a fluorine-free coating containing polydimethylsiloxane(PDMS) and nano TiO2 modified by gamma-aminopropyltriethoxysilane (KH550) is prepared, and then applied on filter paper by roll coating process to create an eco-friendly, one side superhydrophobic paper with excellent mechanical durability. In this coating system, the concentration of TiO2 nanoparticles is up to 20 %, which ensured significant reduction of the amount of organic solvent. The coated side of filter paper has excellent superhydrophobicity, with the contact angle (WCA) of 154.5 degrees +/- 1.5 degrees, and the sliding angle (WSA) of 3.5 degrees +/- 0.5 degrees, but the uncoated side of filter paper remains hydrophilic. The coated surface still has good non-wettability under water jet and water immersion. The resulting surface has good mechanical stability after 40 cycles of tape peeling. Even after 40 sandpaper wear cycles, the coating can still maintain good mechanical stability and superhydrophobicity. In addition, the superhydrophobic coating has a good repulsive effect on different pH solutions and maintains long-term stability in the natural environment for 8 months. The prepared superhydrophobic paper combines the functions of two superwetting surfaces on the same material to better mimic nature and solve complicated real world problems. Such two-sided properties will open up new applications for such paper materials.