Highly hydrophobic cotton fabrics prepared with fluorine-free functionalized silsesquioxanes

Water-repellent finishing of cotton fabrics was carried out using fluorine-free functionalized silsesquioxanes. The modification was performed in two stages: (i) preparation of alkylfunctionalized silsesquioxanes bearing additional triethoxysilyl groups by way of a photochemical thiol-ene click reaction, and (ii) modification of the cotton fibers with these silsesquioxane derivatives. Different ratios of functional groups were investigated and compared with regard to their influence on hydrophobic properties. The hydrophobicity of the cotton fabric was evaluated using the water contact angle test (WCA). Changes in the surface morphology were examined by scanning electron microscopy and atomic force microscopy. In addition, the elemental composition of the treated fabrics was analyzed by energy-dispersive spectroscopy. The most effective and durable derivatives appeared to be those containing four dodecyl groups and four triethoxysilyl groups. The treated surface with WCA of 146° and low roll-off angle (approaching the level of superhydrophobicity) demonstrated considerably higher durability after multiple standard washing cycles.