One-step clean production of robust, superhydrophobic colored Janus fabrics

Clean production of fluorine-free and colorful superhydrophobic surface coating has been highly demanded in many applications but still faces many major challenges. Herein, a one-step clean coating process has been developed to make robust fluorine-free superhydrophobic coating with outstanding color fastness and self-healing property. The coating system comprises cycloolefin copolymer polymer (COC), hexadecyltrimethoxysilane (HDTMS), hydrophobic functionalized TiO2 nanoparticulates and dyeing pigments. Janus cotton fabrics are prepared by applying the TiO2-HDTMS/PB/COC composite coating solution onto the facing side of the fabric by an electrospraying technique. The coated fabric side demonstrates superhydrophobicity showing water contact angle (WCA) of 167.3° ± 2.2° and sliding angle (SA) of 6.9° ± 0.5°, while the un-coated side still retains its original hydrophilic property. The coating shows excellent color fastness and strong bonding strength that can withstand many severe treatments with little affection on color and superhydrophobicity. The coating's original superhydrophobicity can be restored from chemical or physical damages. The developed coating system have also been applied to many other substrates (e.g. polyester, wool, mesh membrane, sponge, etc.). More importantly, the process has low energy consumption with almost no waste liquid produced during the coating process. This simple yet clean coating strategy meets the requirements of green and low energy dyeing, and will benefit the development of robust multifunctional coating.