Superhydrophobic/Superoleophilic Cotton for Efficient Oil–Water Separation Based on the Combined Octadecanoyl Chain Bonding and Polymer Grafting via Surface-Initiated ATRP

This Article reports the facile fabrication of robust and durable superhydrophobic and superoleophilic cotton for highly efficient oil–water separation based on the combination of hydrophobic octadecanoyl chain bonding and polymer grafting via surface-initiated atom transfer radical polymerization (SI-ATRP). Octadecanoyl chain-tethered and polymer-grafted superhydrophobic cotton was obtained by simultaneous treatment with stearoyl chloride and α-bromoisobutyryl bromide to generate hydrophobic cotton bearing initiating sites for ATRP (C18-Cotton-Br), followed by SI-ATRP of acrylonitrile and styrene to obtain polymer-grafted cotton (C18-Cotton-g-PSAN). The surface morphologies, chemical composition, and structural identity of the modified cotton were investigated by scanning electron microscopy (SEM), FT-IR, X-ray photoelectron spectroscopy (XPS), and the nitrogen physisorption experiments. The water contact angle (WCA), oil–water separation, oil absorption, and mechanical properties of the cotton samples were evaluated systematically. The results showed that octadecanoyl and α-bromoisobutyryl groups were successfully bonded on pristine cotton to exhibit hydrophobicity, and further polymer grafting of PSAN was realized with a high grafting density of about 0.47 nm–2. Compared with C18-Cotton-Br, after polymer grafting C18-Cotton-g-PSAN displayed enhanced superhydrophobicity with the WCA increasing from 154° to 159° due to the increased surface roughness. C18-Cotton-g-PSAN exhibited a highly efficient oil–water separation achieving 99.2%, excellent absorption capacity of 26 g/g for toluene with an easily recovered performance, and remarkable mechanical durability withstanding the severe environmental conditions. The biodegradable and recyclable C18-Cotton-g-PSAN demonstrated high selectivity for the absorbing of oil and is expected to become sustainable and highly effective materials for oil-spill cleanup and the oily wastewater treatment from households and industries. Endowed with the robust superhydrophobic durability, the superhydrophobic and superoleophilic cotton can be further woven into cotton fabric to demonstrate their versatilities.