Durable hydrophobic cotton surfaces prepared using silica nanoparticles and multifunctional silanes

Durable non-fluorine hydrophobic cotton surfaces were obtained by treating woven cotton fabrics using combinations of silica nanoparticles and multifunctional silanes. Both the hydrophobicity and durability of treated cotton surfaces were controlled by selectively adjusting the alkyl chain length of silane hydrophobes and the surface chemistry, surface area, and content of silica nanoparticles. It was found that with an increase in the alkyl chain length of the silane hydrophobes, the hydrophobicity of treated cotton surfaces increased: the maximum surface durability was obtained at an alkyl chain length of 12 carbon atoms. Hydrophilic silica nanoparticles significantly improved the hydrophobicity and durability of treated cotton surfaces, whereas the hydrophobic silica nanoparticles were found to reduce them. The surface area of the silica nanoparticles did not have a significant impact on the cotton fabric hydrophobicity, however, a larger silica surface area resulted in better durability. The highest hydrophobicity (a contact angle of 142 degrees) and the best durability (a 95.7% recovery of contact angle after heavy-duty industrial laundering) were achieved when treating cotton surfaces with the silane tetramethoxysilane crosslink enhancer, silane n-dodecyltrimethoxysilane hydrophobe (alkyl chain length = 12 carbon atoms), and 0.2% hydrophilic silica nanoparticles with a diameter of 12 nm.