Micro-nanostructure-based super-hydrophobic surface on cotton fabric

Inspired by the super water repellency owing to the hierarchal micro- and nano-structural features observed in nature, we constructed similar hierarchal surfaces in both micro and nano sizes on cotton fabrics via a two-step sol-gel method. Silica sol-gel particles were prepared by the modified Stober method of hydrolysis and condensation of tetraethylorthosilicate as a precursor. Through adjusting the volume of NH3 center dot H2O, particles of various sizes were obtained. Using the dip-pad-dry-cure method, the cotton fabrics were finished with the silica sol gels of micro- and nano-sizes, and followed by low surface energy modification of hexadecyltrimethoxysilane. The results showed that the thus structured surface made the cotton fabrics much more hydrophobic with a water contact angle near 162(O), close to that of the lotus leaf.