Photocatalytic Layer-by-Layer Coatings for Degradation of Acutely Toxic Agents

Highly reactive layer-by-layer (LbL) films have been developed as protective coatings intended for application on fibers worn by military personnel. In this work, the anionic species are titanium dioxide nanoparticles ranging from 5 to 10 nm in size, which are prepared in a stable colloidal solution specifically designed for this application, while the cationic species can be one of several traditional synthetic polycations, including weak and strong polyelectrolytes. The resulting coatings are mechanically stable and offer selective protection when the wearer is exposed to UV radiation (e.g.,sunlight); whereas the inherent water transmissive nature of the multilayers allows for much greater water vapor transport rates as compared to an inert rubber barrier material. Permeation tests of coated materials were conducted in a specially engineered cell by exposing the materials to a CWA simulant. In the extreme case, when a coated material is subjected to a saturated vapor of the CWA simulant, UV exposure resulted in a 95% decrease in toxic agent permeation. Furthermore, the coating can be deposited via a spray-LbL technique developed specifically for rapid, uniform deposition over large areas of textile materials at ambient temperatures and moderate pressures.