Bio-inspired and facile fabrication strategy of bio-based, halogen-free and superhydrophobic cotton fabrics with multi-functionality and durability

To satisfy the needs of cotton fabrics in the aspect of multi-functionality and durability, a layer-by-layer (LBL) decomposition technique was exploited, inspired by natural superhydrophobicity. Significantly, an intumescent flame retardant system consisting of bio-based phytic acid (PA) and polyethyleneimine (PEI) was used to improve the flame retardancy of cotton fabrics. Then, polydimethylsiloxane (PDMS) was deposited to reduce the surface energy of cotton fabrics, which endows the superhydrophobic properties of cotton fabrics with low adhesion. The results have shown that the water contact angle and sliding angle of as-prepared cotton fabrics reach 154° and 8°, respectively. Most of all, the multifunctional cotton fabrics have also achieved excellent self-cleaning and oil-water separation function with excellent durability and stability, which can maintain the superhydrophobicity after 24 h strong acid and alkali corrosion tests, 360 cm abrasion distance, 5 times oxygen plasma etching-restoration cycles, 5 times laundry tests, 22 times tape adhesive-peel tests and knife cutting tests. Moreover, superhydrophobic cotton fabrics exhibited good flame retardancy with self-extinguishing ability. Therefore, the superhydrophobic cotton fabrics have exhibited the characteristics of robust, environmental protection, environmental friendliness, low cost and easy preparation, which provided a feasible strategy for all-weather superhydrophobic needs in extreme environments, especially in firefighting uniforms and scenarios with high fire safety requirements.