Facile Fabrication of Robust and Fluorine-Free Superhydrophobic PDMS/STA-Coated Cotton Fabric for Highly Efficient Oil-Water Separation

Oil-water separation using special wettability materials has received much attention due to its low energy consumption and high separation efficiency. Herein, a fluorine-free superhydrophobic cotton fabric(PDMS/STA -coated cotton fabric) was successfully prepared by a simple impregnation method using hydroxyl-capped polydimethylsiloxane (PDMS-OH), tetraethoxysilane (TEOS) and stearic acid (STA) as precursors. The Investigation found that the cross-linking reactions between the hydroxyl groups form PDMS-OH, hydrolyzed TEOS made a strong interact of PDMS-OH and cotton fabric. Besides, a suitable roughness surface of coated cotton fabric was established by introducing STA due to its long chain-structure. The contact angle of this composite can reach 158.7°under optical condition due to its low surface energy and desired roughness. The oil/water separation efficiency of PDMS/STA-coated cotton fabric is higher than 90% even after 10 cycles of oil-water separation, the oil flux can reach 11862.42 L m-2 h-1. In addition, PDMS/STA-coated cotton fabric exhibits excellent chemical stability and durability under extreme conditions such as strong acid (HCl, pH=1~2) and alkali (NaOH, pH=13~14), the hydrophobicity of PDMS/STA-coated cotton fabric was decreased to 147° even after 350 cycles of abrasion testing.