Water-Based Flame Retardant Nanocoatings from Environmentally-Benign Ingredients

Jaime Grunlan, Department of Mechanical Engineering, Texas A&M University, College Station, United States


Layer-by-layer (LbL) assembly is a conformal coating “platform” technology capable of imparting a multiplicity of functionalities on nearly any type of surface in a relatively environmentally friendly way. At its core, LbL is a solution deposition technique in which layers of cationic and anionic ingredients are built up via electrostatic attractions in an alternating fashion. This presentation will highlight LbL-based flame retardant nanocoatings for polyester-cotton fabric. Using chitosan and an insoluble phosphorus source in alternating layers, less than 15 wt% coating is necessary to impart self-extinguishing properties to the fabric. Immediate self-extinguishment in the vertical flame test and a significant reduction of peak heat release of the fabric are the result of this coating. This commercially-feasible and environmentally-benign technology imparts a flame retardant treatment to one of the most commonly used fabric types. In an effort to impart flame retardant behavior to fabric using fewer processing steps, a water-soluble polyelectrolyte complex (PEC) was devloped. This nanocoating is comprised of polyethylenimine and poly(sodium phosphate) and imparts self-extinguishing behavior to cotton fabric in just a single coating step. Adding a melamine solution to the coating procedure renders nylon-cotton blends self-extinguishing. These blends are widely used for apparel and equipment. More recently, a PEC coating was developed for polyester-cotton. It passes vertical flame testing after five standard washes or 8 hours in boiling water. Our flame retardant work has been highlighted in C&EN, ScienceNews, Nature, Smithsonian Magazine, Chemistry World and various scientific news outlets worldwide. For more information, please visit: http://nanocomposites.tamu.edu