عنوان مقاله [English]
Polyurethane foams (PUFs) are the largest group of polyurethane products and can be
classified into rigid and flexible foams. Rigid polyurethane foams are mainly used for
heat insulation in refrigeration, construction, and partly in automotive industry. Flexible
polyurethane foams can be also widely used in fabrication of car seat and furniture industry.
In general, due to the porous structure, large surface area, and good air permeability,
polyurethane foams are highly flammable. Flame retardants containing phosphorus,
halogen, nitrogen and silicon can partially reduce the flammability of polyurethane foams.
Also, the presence of thermally stable groups such as carbodiimide, isocyanurate, and
nitrogen-containing heterocycles in the structure of polyurethane foams can increase their
fire resistance. Over the past two decades, a new technique called layer-by-layer (LbL)
assembly has been introduced for the preparation of flame retardant nanostructured coatings
on the surfaces of polymeric foams. In this method, polymers, nanoparticles and various
compounds are placed in thin layers through secondary interactions such as electrostatic
forces, hydrogen bonds and van der Waals interactions on the surface of polymeric foam.
In this paper, a brief review on the combustion and flame retardancy of polyurethane foams,
layer-by-layer assembly technique and its application in improving the fire resistance of
polyurethane foams, flame retardation mechanism of LbL coatings and different types of
these coatings were presented. Finally, suggestions for improving the efficiency of LbL
coatings are discussed.