Nanocoating of starch and clay that reduces the flammability of polyurethane foam

In an effort to reduce the flammability of flexible polyurethane foam, a thin polyelectrolyte multilayer coating comprising cationic starch and montmorillonite (MMT) or vermiculite (VMT) clay was deposited through layer-by-layer (LbL) assembly. These nanocoatings were characterized with electron microscopy, direct flame exposure and cone calorimetry. All coatings are conformal and maintain the shape of the foam after exposure to an open flame. Cone calorimetry revealed that five bilayers (BLs) of starch/clay reduce the peak heat release rate of foam by 54%, while ten BL coatings reduce the total smoke release by 39 and 67% with MMT and VMT, respectively. These results demonstrate one of the most efficient and renewable nanocoatings prepared using LbL assembly for reducing the flammability of flexible polyurethane foam.