Modified Silica Sol Coatings for Highly Hydrophobic Cotton and Polyester Fabrics Using a One-Step Procedure

The applications of water-resistant and stain-resistant finishes to apparel have become widespread in recent years due to high consumer demand. In our previous research, we studied the formation of highly hydrophobic surfaces on cotton and polyester fabrics using a two-step treatment procedure, i.e., first forming silica sol by hydrolysis and subsequent condensation of tetraethoxysilane under alkaline conditions, applying the sol to the surfaces of cotton and polyester fabrics, and then applying hydrolyzed hexadecyltrimethoxysilane on the treated fabrics to impart hydrophobicity to the surfaces of the fabrics. In this research, we developed a novel one-step procedure to form highly hydrophobic surfaces on cotton and polyester fabrics using different modified silica sols. The first series of modified silica sol ('sol A") was prepared by the reactions of a sol formed by alkaline hydrolysis of tetraethoxysilane and alkyltrialkoxysilanes in a NH(4)OH ethanol solution. A second series ("sol B") was prepared by the reactions of a sot formed by the same method, followed by adding (3-glycidyloxypropyl)trimethoxysilane and alkyltrialkoxysilanes to the sol. The cotton and polyester fabrics treated with the two modified silica sol systems showed excellent water repellency with the water contact angle above 150 degrees on cotton and above 140 degrees on polyester under the optimum treatment conditions. The treated cotton and polyester had significantly improved hydrolysis resistance and maintained high levels of hydrophobicity after 30 laundering cycles.