Using a lotus leaf as our model, we fabricated an extremely low surface energy micro/nanostructured coating for textiles that repel oil, water, and chemical warfare agents (CWAs) using a simple process that is suitable for large scale production. This coating, called "OmniBlock", consisted of approximately 200-nm silica nanoparticles, tetraethylorthosilicate, 3-glycidoxypropyl trimethoxysilane, and a perfluorooctanoic acid-free fluoropolymer (Fluorolink S10) that was cross-linked between Si-O-Si groups via a sol-gel process. The perfluorooctanoic acid-free fluoropolymer-coated silica nanoparticles were simply applied to the surface of a cotton fabric by a dip-dry-cure process, forming dense, continuous, and uniform layers of OmniBlock coating. OmniBlock modified the surface of the cotton fibers, creating a rough, high surface area uniform coating with many micro-crevasses. As a result, n-dodecane, water, and CWAs beaded up without wetting the surface, exhibiting large contact angles of 154° for water and 121° for n-dodecane, with a small shedding angle of 5° and contact angle hysteresis of 3.2° for water. The designed coating showed excellent liquid repellence properties against three types of CWAs: 129°, 72°, and 87° for sulfur mustard (HD), soman (GD), and VX nerve agents, respectively. Furthermore, OmniBlock coating shows good mechanical properties under tensile strength and wash tests. This remarkable ability to repel CWAs is likely to have potential military applications in personal protective equipment systems requiring self-cleaning functions.
Keywords: OmniBlock; chemical warfare agent; coating; textile.