Application of modified SiO_2 hydrosol to superhydrophobic finish of cotton fabrics

Modified SiO2 hydrosol was prepared by water-based sol-gel method using methyltrime-thoxysilane(MTMOS) as the precursor,hexadecyltrimethoxysilane(HDTMS) as a hydrophobic additive,and ammonia as a catalyst,in the presence of anionic surfactant sodium dodecyl benzenesulfonate(SDBS).Superhydrophobic cotton fabrics were successfully obtained by dip-coating the modified SiO2 hydrosol.By controlling ammonia amount and surfactant concentration,the modified SiO2 hydrosols with different particle sizes and particle size distributions were prepared.The effect of the SiO2 nanoparticle size and distribution on the water-repellent property of the treated cotton fabrics was discussed.The treated cotton fabrics were characterized by scanning electron microscopy(SEM),atomic force microscopy(AFM),and X-ray photoelectron spectroscopy(XPS).The results showed that the modified SiO2 nanoparticles had been coated onto the cotton fiber surface,resulting in lowerd surface energy and increased surface roughness.The testing of water-repellent property of the treated cotton fabrics demonstrated that the water contact angle and water sliding angle of the treated fabric were 152.1° for a 5μL droplet and 8° for a 15μL droplet,respectively,and the spray rating was 100,thus realizing superhydrophobicity.The physical and mechanical properties measurement of the treated fabrics showed little change except the permeability lowered slightly compared with untreated ones.