Multifunctional bionic hydrophobic cotton fabrics modified with cationic nano-SiO2/polyurethane acrylate

In recent years, SiO₂ has gained widespread application in the hydrophobic finishing of cotton textiles due to its exceptional versatility and robust controllability. However, the inherent negative charge on the surface of SiO₂ results in inadequate adhesion on fabrics and incompatibility with cationic hydrophobic agents. In this work, a cationic nano-silica (DI-SiO₂) material was prepared by introducing cationic groups and reactive groups onto the silica surface using silane coupling agents to enhance the compatibility between silica and cationic polyurethane acrylate as well as the durability of hydrophobic cotton fabrics. It was found that DI-SiO₂ exhibits a significantly high zeta potential (40 mV ± 5 mV) and excellent compatibility in polyurethane acrylate dispersions without obvious demulsification and sedimentation after 24 h of storage. The as-prepared water-repellent agent consisting of DI-SiO₂ and polyurethane acrylate could chemically bond to cotton fabrics, thereby forming a uniform, robust, and long-lasting water-repellent film on the fabric surface with the water contact angle (WCA) exceeding 150°. In addition, the hydrophobic cotton fabric exhibited superior robustness and durability, maintaining high water repellency (WCA > 125°) after treatment with acids, alkalis, organic solvents, UV irradiation, abrasion, and repeated washing. More importantly, the modified cotton fabric possesses excellent self-cleaning, breathability, moisture permeability, and oil-water separation properties. These outstanding features render it highly valuable for applications in fields such as mountaineering and camping.