Cotton fabric was treated with flame-retardant coatings composed of branched polyethylenimine (BPEI) and sodium montmorillonite (MMT) clay, prepared via layer-by-layer (LbL) assembly. Four coating recipes were created by exposing fabric to aqueous solutions of BPEI (pH 7 or 10) and MMT (0.2 or 1 wt %). BPEI pH 10 produces the thickest films, while 1 wt % MMT gives the highest clay loading. Each coating recipe was evaluated at 5 and 20 bilayers. Thermogravimetric analysis showed that coated fabrics left as much as 13% char after heating to 500 degrees C, nearly 2 orders of magnitude more than uncoated fabric, with less than 4 wt % coming from the coating itself. These coatings also reduced afterglow time in vertical flame tests. Postburn residues of coated fabrics were examined with SEM and revealed that the weave structure and fiber shape in all coated fabrics were preserved. The BPEI pH 7/1 wt % MMT recipe was most effective. Microcombustion calorimeter testing showed that all coated fabrics reduced the total heat release and heat release capacity of the fabric. Fiber count and strength of uncoated and coated fabric are similar. These results demonstrate that LbL assembly is a relatively simple method for imparting flame-retardant behavior to cotton fabric. This work lays the foundation for using these types of thin film assemblies to make a variety of complex substrates (foam, fabrics, etc.) flame resistant.

An intumescent nanocoating composed of poly(allylamine) and poly(sodium phosphate) is deposited layer‐by‐layer on cotton fabric. Fire is extinguished right after ignition on the fabric during vertical flame testing. The individual fibers are conformally coated and bubbles form on the fiber surfaces during burning, which is due to an intumescent effect.

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Cotton fabric is the most used natural textile, but it is highly flammable. By treating fabric with intumescent nanocoatings, composed of nitrogen‐rich and phosphorous‐rich polymers and prepared via layer‐by‐layer (LbL) assembly, the cotton fabric can be rendered anti‐flammable. In some cases, no ignition occurs, as reported by Jaime C. Grunlan and co‐workers . The cover photograph is a dramatization created by Texas A&M Engineering graphic designer Charlie Apel.