Robust fluorine-free and self-healing superhydrophobic coatings by H3BO3 incorporation with SiO2-alkyl-silane@PDMS on cotton fabric

Limited robustness is a serious drawback for superhydrophobic coatings, and degrades the performance of superhydrophobic surfaces in practical applications. Although fluoro-reagents have excellent durability for superhydrophobicity, their use has been restricted due to various health and environmental concerns. In this work, we describe a facile and efficient fabrication strategy for creating robust fluorine-free superhydrophobic composite coatings that are prepared by a simple dip-dry method, in which the H3BO3-incorporated SiO2-alkyl-silane coatings are deposited on woven cotton fabric surfaces followed by polydimethylsiloxane (PDMS) modification. The coated surface shows a large water contact angle of 157.95˚±2˚ and a small sliding hysteresis angle of 3.8˚±0.6˚, demonstrating excellent superhydrophobicity. The coated fabric surface also exhibited robustness and durability, withstanding a tape-peeling test (under 48.05 kPa) for around 80 repetitions and sandpaper rubbing (loaded 100 g) for 40 cycles. Furthermore, the coated fabric surface displayed self-healing and oil-water separation capacities. The developed superhydrophobic coatings in this study are robust, environmentally benign, and easy to fabricate, showing promising applications in textile industries.