Nonfluorinated Superhydrophobic Chemical Coatings on Polyester Fabric Prepared with Kinetically Controlled Hydrolyzed Methyltrimethoxysilane

Nonfluorinated chemical coatings to generate durable water repellency have become increasingly important as a method of improving materials and product performance. Here we report a kinetically controlled fabrication of superhydrophobic polyester fabrics via one-step dip-coating in water-based solutions of fluorine-free hydrolyzed methyltrimethoxysilane (MTMS). The hydrophobicity of coated fabrics was tuned by varying the morphologies of surface-coated silica layers from smooth thin film to hierarchical structures. This was achieved by systematically altering MTMS solution pH and reaction time to control the reaction kinetics of hydrolysis and polymerization. These results offer a new strategy and approach toward fabrication of superhydrophobic coatings with tunable hierarchy. The mechanism of MTMS reaction with NH4OH catalyst was investigated with FTIR and multiangle dynamic light scattering (MADLS) for improved coating performance. The stability and durability of MTMS coatings were carefully verified after washing and accelerated weathering tests through contact angle, spray test, and XPS analysis. Impact contact angle (ICA) was invoked to quickly assess liquid droplet adhesion after surface impact; this test proffers a viable substitute for the standard AATCC 22-2005 spray test. The technology presented here can be extended to other organosilanes with one functional group and three hydrolyzable methoxy substituents to allow a variety of surface functionalities and open a wide range of applications in the field of green surface chemistry modifications.