Preparation of fluorine-free robust superhydrophobic fabric via diazonium radical graft polymerization

Abstract

A kind of environmentally friendly superhydrophobic cotton fabric (CF) was prepared via diazonium chemistry and subsequent facile solution chemistry. Typically, a polymer layer of benzoic acid was grafted on CF surface through in-situ diazonium radical polymerization, which provided abundant active sites of carboxy group to effectively graft with fluorine-free long carbon chain alkyl groups by covalent bonding, forming hydrophobic polymer brushes on the fiber surface with great mechanical durability. Here, the effect of reaction conditions on the morphology and wettability of modified fabric surfaces were systematically investigated. In addition, the grafting mechanism of the modification was analyzed by chemical structure characterization. Owing to the synergistic effect of micro-nano roughing structures and low surface energy materials, the WCA of modified fabric was up to 156.3°, exhibiting excellent superhydrophobic performance. Compared to the pristine CF, the modified fabric well maintained its original air permeability, flexural rigidity and mechanical strength. More importantly, the superhydrophobic fabric could be against >150 min and 50 cycles of laundering and abrasion, respectively, exhibiting good mechanical durability. Even heating at 100 °C for 5 h, the prepared cotton fabric still maintained its hydrophobic properties, and the contact angle reached 154.5°. It is noteworthy that the prepared fabric could effectively separate the oil-water mixture with a separation efficiency of up to 98.4 %. Therefore, this facile grafting method opens up a new avenue to prepare fluorine-free environmentally friendly superhydrophobic fabrics.