Flame-retardant surface treatments


Flame retardants mitigate the threat of fire from inherently flammable materials responsible for sustaining a high standard of living. Although bulk flame retardants have proven effective for many years, there is now increased interest in the use of surface treatments to localize flame-retardant chemistry at the exterior of a material, where combustion occurs, in an effort to preserve desirable bulk properties and minimize the amount of additive needed. This Review provides a historical overview that leads to the most promising surface treatments that will help pave the way for developing more effective and non-intrusive flame retardants in the future. The way in which a fire transpires, and the various chemistries and mechanisms used to counteract fire propagation, are discussed. Challenges that remain to improve current flame-retardant surface treatments are also addressed, as the success of these treatments depends on the scalability, durability and ability to impart desired functionality without conferring environmental problems.

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Fig. 1: Mechanism for combustion and flame-retardant modes of action.
Fig. 2: Examples of impregnation-based flame-retardant chemistry.
Fig. 3: Plasma-assisted surface treatment.
Fig. 4: Sol–gel surface treatment.
Fig. 5: Polyelectrolyte treatments include layer-by-layer assembled coatings and directly deposited polyelectrolyte coatings.


  1. 1.

    Brushlinsky, N. N., Ahrens, M., Sokolov, S. V. & Wagner, P. World fire statistics. CTIF https://www.ctif.org/world-fire-statistics (2018).

  2. 2.

    BBC News. How the tragedy unfolded at Grenfell Tower. BBC https://www.bbc.co.uk/news/uk-england-london-40272168 (2018).

  3. 3.

    BBC News. Notre-Dame: massive fire ravages Paris cathedral. BBC https://www.bbc.co.uk/news/world-europe-47941794 (2019).

  4. 4.

    Morgan, A. B. & Wilkie, C. A. in Fire Retardancy of Polymeric Materials 2nd edn 1–14 (CRC, 2010).

  5. 5.

    Birnbaum, L. S. & Staskal, D. F. Brominated flame retardants: cause for concern? Environ. Health Perspect. 112, 9–17 (2004).

  6. 6.

    Hahladakis, J. N., Velis, C. A., Weber, R., Iacovidou, E. & Purnell, P. An overview of chemical additives present in plastics: migration, release, fate and environmental impact during their use, disposal and recycling. J. Hazard. Mater. 344, 179–199 (2018).

  7. 7.

    Green, J. Mechanisms for flame retardancy and smoke suppression – a review. J. Fire Sci. 14, 426–442 (1996).

  8. 8.

    Laoutid, F., Bonnaud, L., Alexandre, M., Lopez-Cuesta, J.-M. & Dubois, P. New prospects in flame retardant polymer materials: from fundamentals to nanocomposites. Mater. Sci. Eng. R Rep. 63, 100–125 (2009).

  9. 9.

    Wilson, W. E. Jr & Fristrom, R. M. Radicals in flames. APL. Tech. Dig. 2, 2–7 (1963).

  10. 10.

    Janbozorgi, M., Far, K. & Metghalchi, H. in Handbook of Combustion Vol. 1 (ed. Lackner, M.) 1–25 (Wiley-VCH, 2010).

  11. 11.

    Boryniec, S. & Przygocki, W. Polymer combustion processes. 3. Flame retardants for polymeric materials. Prog. Rubber Plast. Recycl. Technol. 17, 127–148 (2001).

  12. 12.

    Kashiwagi, T. Polymer combustion and flammability—Role of the condensed phase. Symp. (Int.) Combust. 25, 1423–1437 (1994).

  13. 13.

    Camino, G., Costa, L. & Luda di Cortemiglia, M. P. Overview of fire retardant mechanisms. Polym. Degrad. Stab. 33, 131–154 (1991).

  14. 14.

    Shaw, S. Halogenated flame retardants: do the fire safety benefits justify the risks? Rev. Environ. Health 25, 261–305 (2010).

  15. 15.

    Shen, K. K. in Non-Halogenated Flame Retardant Handbook (eds Morgan, A. B. & Wilkie, C. A.) 201–241 (Wiley, 2014).

  16. 16.

    Kilinc, M. Silicon Based Flame Retardants (Scrivener, 2014).

  17. 17.

    Brown, S. C. in Plastic Additives: An A-Z Reference (ed. Pritchard, G.) 287–296 (Springer, 1998).

  18. 18.

    Morgan, A. B., Cusack, P. A. & Wilkie, C. A. in Non-Halogenated Flame Retardant Handbook (eds Morgan, A. B. & Wilkie, C. A.) 347–403 (Wiley, 2014).

  19. 19.

    Schartel, B. Phosphorus-based flame retardancy mechanisms—Old hat or a starting point for future development? Materials 3, 4710–4745 (2010).

  20. 20.

    Salmeia, K., Gaan, S. & Malucelli, G. Recent advances for flame retardancy of textiles based on phosphorus chemistry. Polymers 8, 319 (2016).

  21. 21.

    Salmeia, K., Fage, J., Liang, S. & Gaan, S. An overview of mode of action and analytical methods for evaluation of gas phase activities of flame retardants. Polymers 7, 504–526 (2015).

  22. 22.

    Schartel, B. et al. Flame retardancy of polymers: the role of specific reactions in the condensed phase. Macromol. Mater. Eng. 301, 9–35 (2016).

  23. 23.

    Velencoso, M. M., Battig, A., Markwart, J. C., Schartel, B. & Wurm, F. R. Molecular firefighting — how modern phosphorus chemistry can help solve the challenge of flame retardancy. Angew. Chem. Int. Ed. Engl. 57, 10450–10467 (2018).

  24. 24.

    Klatt, M. Nitrogen-based Flame Retardants (Scrivener, 2014).

  25. 25.

    Schartel, B., Wilkie, C. A. & Camino, G. Recommendations on the scientific approach to polymer flame retardancy: part 2—Concepts. J. Fire Sci. 35, 3–20 (2017).

  26. 26.

    Horacek, H. & Grabner, R. Advantages of flame retardants based on nitrogen compounds. Polym. Degrad. Stab. 54, 205–215 (1996).

  27. 27.

    Vandersall, H. L. Intumescent coating systems, their development and chemistry. J. Fire Flamm. 2, 97–140 (1971).

  28. 28.

    Guin, T., Krecker, M., Milhorn, A. & Grunlan, J. C. Maintaining hand and improving fire resistance of cotton fabric through ultrasonication rinsing of multilayer nanocoating. Cellulose 21, 3023–3030 (2014).

  29. 29.

    Smith, R. J. et al. Environmentally benign halloysite nanotube multilayer assembly significantly reduces polyurethane flammability. Adv. Funct. Mater. 28, 1703289 (2018).

  30. 30.

    Holder, K. M., Huff, M. E., Cosio, M. N. & Grunlan, J. C. Intumescing multilayer thin film deposited on clay-based nanobrick wall to produce self-extinguishing flame retardant polyurethane. J. Mater. Sci. 50, 2451–2458 (2015).

  31. 31.

    Hull, T. R. in Advances in Fire Retardant Materials (eds Horrocks, A. R. & Price, D.) 255–290 (Woodhead, 2008).

  32. 32.

    Dombrowski, R. Flame retardants for textile coatings. J. Coat. Fabr. 25, 224–238 (1996).

  33. 33.

    Wang, M. Y. et al. Flame retardant textile back-coatings. part 1: antimony-halogen system interactions and the effect of replacement by phosphorus-containing agents. J. Fire Sci. 18, 265–294 (2000).

  34. 34.

    Horrocks, A. R., Wang, M. Y., Hall, M. E., Sunmonu, F. & Pearson, J. S. Flame retardant textile back-coatings. part 2. Effectiveness of phosphorus-containing flame retardants in textile back-coating formulations. Polym. Int. 49, 1079–1091 (2000).

  35. 35.

    Giraud, S. et al. Flame retarded polyurea with microencapsulated ammonium phosphate for textile coating. Polym. Degrad. Stab. 88, 106–113 (2005).

  36. 36.

    Davies, P. J., Horrocks, A. R. & Alderson, A. The sensitisation of thermal decomposition of ammonium polyphosphate by selected metal ions and their potential for improved cotton fabric flame retardancy. Polym. Degrad. Stab. 88, 114–122 (2005).

  37. 37.

    Horrocks, A. R., Davies, P. J., Kandola, B. K. & Alderson, A. The potential for volatile phosphorus-containing flame retardants in textile back-coatings. J. Fire Sci. 25, 523–540 (2007).

  38. 38.

    Wesolek, D. & Gieparda, W. Single- and multiwalled carbon nanotubes with phosphorus based flame retardants for textiles. J. Nanomaterials 2014, 15 (2014).

  39. 39.

    Wesolek, D., Gasiorowski, R., Rojewski, S., Walentowska, J. & Wojcik, R. New flexible flame retardant coatings based on siloxane resin and ethylene-vinyl chloride copolymer. Polymers 8, 419 (2016).

  40. 40.

    Reeves, W. A. & Guthrie, J. D. Intermediate for flame-resistant polymers - reactions of tetrakis(hydroxymethyl)phosphonium chloride. Ind. Eng. Chem. 48, 64–67 (1956).

  41. 41.

    Cashen, N. A. & Reinhardt, R. M. Flame-retardant coating based on THPOH-dimethylolurea-NH3 for cellulosic and cellulosic-blend fabrics. Text. Res. J. 46, 899–903 (1976).

  42. 42.

    Jiang, Y. et al. Study on a novel multifunctional nanocomposite as flame retardant of leather. Polym. Degrad. Stab. 115, 110–116 (2015).

  43. 43.

    Zope, I. S., Foo, S., Seah, D. G. J., Akunuri, A. T. & Dasari, A. Development and evaluation of a water-based flame retardant spray coating for cotton fabrics. ACS Appl. Mater. Interfaces 9, 40782–40791 (2017).

  44. 44.

    National Research Council (US) Subcommittee on Flame-Retardant Chemicals. Toxicological Risks of Selected Flame-Retardant Chemicals (National Academies Press, 2000).

  45. 45.

    Wu, W. & Yang, C. Q. Comparison of different reactive organophosphorus flame retardant agents for cotton: part I. The bonding of the flame retardant agents to cotton. Polym. Degrad. Stab. 91, 2541–2548 (2006).

  46. 46.

    Yang, H. & Yang, C. Q. Flame retardant finishing of nylon/cotton blend fabrics using a hydroxy-functional organophosphorus oligomer. Ind. Eng. Chem. Res. 47, 2160–2165 (2008).

  47. 47.

    Li, Y. et al. Durable flame retardant and antibacterial finishing on cotton fabrics with cyclotriphosphazene/polydopamine/silver nanoparticles hybrid coatings. Appl. Surf. Sci. 435, 1337–1343 (2018).

  48. 48.

    Yang, C. Q. & Wu, W. Combination of a hydroxy-functional organophosphorus oligomer and a multifunctional carboxylic acid as a flame retardant finishing system for cotton: part I. The chemical reactions. Fire Mater. 27, 223–237 (2003).

  49. 49.

    Yang, C. Q. & Wu, W. Combination of a hydroxy-functional organophosphorus oligomer and a multifunctional carboxylic acid as a flame retardant finishing system for cotton: part II. Formation of calcium salt during laundering. Fire Mater. 27, 239–251 (2003).

  50. 50.

    Liu, W., Chen, L. & Wang, Y.-Z. A novel phosphorus-containing flame retardant for the formaldehyde-free treatment of cotton fabrics. Polym. Degrad. Stab. 97, 2487–2491 (2012).

  51. 51.

    Bosco, F. et al. Thermal stability and flame resistance of cotton fabrics treated with whey proteins. Carbohydr. Polym. 94, 372–377 (2013).

  52. 52.

    Yang, C. Q. & Chen, Q. Flame retardant finishing of the polyester/cotton blend fabric using a cross-linkable hydroxy-functional organophosphorus oligomer. Fire Mater. 43, 283–293 (2019).

  53. 53.

    Yuan, H., Xing, W., Zhang, P., Song, L. & Hu, Y. Functionalization of cotton with UV-cured flame retardant coatings. Ind. Eng. Chem. Res. 51, 5394–5401 (2012).

  54. 54.

    Kim, S. J. & Jang, J. Synergistic UV-curable flame-retardant finish of cotton using comonomers of vinylphosphonic acid and acrylamide. Fibers Polym. 18, 2328–2333 (2017).

  55. 55.

    Yang, C. & Chen, Q. Heat release property and fire performance of the Nomex/cotton blend fabric treated with a nonformaldehyde organophosphorus system. Polymers 8, 327 (2016).

  56. 56.

    Cho, J. H. et al. Bioinspired catecholic flame retardant nanocoating for flexible polyurethane foams. Chem. Mater. 27, 6784–6790 (2015).

  57. 57.

    Kim, H. et al. Polydopamine-graphene oxide flame retardant nanocoatings applied via an aqueous liquid crystalline scaffold. Adv. Funct. Mater. 28, 1803172 (2018).

  58. 58.

    Xu, F. et al. Highly efficient flame-retardant and soft cotton fabric prepared by a novel reactive flame retardant. Cellulose 26, 4225–4240 (2019).

  59. 59.

    Blanchard, E. J. & Graves, E. E. Phosphorylation of cellulose with some phosphonic acid derivatives. Text. Res. J. 73, 22–26 (2003).

  60. 60.

    Feng, Y. et al. A plant-based reactive ammonium phytate for use as a flame-retardant for cotton fabric. Carbohydr. Polym. 175, 636–644 (2017).

  61. 61.

    Dong, C. et al. Preparation and properties of cotton fabrics treated with a novel antimicrobial and flame retardant containing triazine and phosphorus components. J. Therm. Anal. Calorim. 131, 1079–1087 (2018).

  62. 62.

    Liu, X. et al. Preparation of durable and flame retardant lyocell fibers by a one-pot chemical treatment. Cellulose 25, 6745–6758 (2018).

  63. 63.

    Xu, L., Wang, W. & Yu, D. Durable flame retardant finishing of cotton fabrics with halogen-free organophosphonate by UV photoinitiated thiol-ene click chemistry. Carbohydr. Polym. 172, 275–283 (2017).

  64. 64.

    Wang, L.-H. et al. Fire retardant viscose fiber fabric produced by graft polymerization of phosphorus and nitrogen-containing monomer. Cellulose 23, 2689–2700 (2016).

  65. 65.

    Tendero, C., Tixier, C., Tristant, P., Desmaison, J. & Leprince, P. Atmospheric pressure plasmas: a review. Spectrochim. Acta. B At. Spectrosc. 61, 2–30 (2006).

  66. 66.

    Akovali, G. & Gundogan, G. Studies on flame retardancy of polyacrylonitrile fiber treated by flame-retardant monomers in cold plasma. J. Appl. Polym. Sci. 41, 2011–2019 (1990).

  67. 67.

    Bourbigot, S. et al. New approach to flame retardancy using plasma assisted surface polymerisation techniques. Polym. Degrad. Stab. 66, 153–155 (1999).

  68. 68.

    Schartel, B., Kühn, G., Mix, R. & Friedrich, J. Surface controlled fire retardancy of polymers using plasma polymerisation. Macromol. Mater. Eng. 287, 579–582 (2002).

  69. 69.

    Errifai, I. et al. Elaboration of a fire retardant coating for polyamide-6 using cold plasma polymerization of a fluorinated acrylate. Surf. Coat. Technol. 180–181, 297–301 (2004).

  70. 70.

    Tsafack, M.-J., Hochart, F. & Levalois-Grützmacher, J. Polymerization and surface modification by low pressure plasma technique. Eur. Phys. J. Appl. Phys. 26, 215–219 (2004).

  71. 71.

    Tsafack, M. J. & Levalois-Grützmacher, J. Towards multifunctional surfaces using the plasma-induced graft-polymerization (PIGP) process: Flame and waterproof cotton textiles. Surf. Coat. Technol. 201, 5789–5795 (2007).

  72. 72.

    Yavuz, H., Rzaev, Z. & Dilsiz, N. Characterisation of flame retardant plasma polymer deposited BOPP film. Plast. Rubber Compos. 37, 268–275 (2008).

  73. 73.

    Horrocks, A. R., Nazaré, S., Masood, R., Kandola, B. & Price, D. Surface modification of fabrics for improved flash-fire resistance using atmospheric pressure plasma in the presence of a functionalized clay and polysiloxane. Polym. Adv. Technol. 22, 22–29 (2011).

  74. 74.

    Hilt, F., Gherardi, N., Duday, D., Berné, A. & Choquet, P. Efficient flame retardant thin films synthesized by atmospheric pressure PECVD through the high co-deposition rate of hexamethyldisiloxane and triethylphosphate on polycarbonate and polyamide-6 substrates. ACS Appl. Mater. Interfaces 8, 12422–12433 (2016).

  75. 75.

    Carosio, F., Alongi, J. & Frache, A. Influence of surface activation by plasma and nanoparticle adsorption on the morphology, thermal stability and combustion behavior of PET fabrics. Eur. Polym. J. 47, 893–902 (2011).

  76. 76.

    Kamlangkla, K., Hodak, S. K. & Levalois-Grützmacher, J. Multifunctional silk fabrics by means of the plasma induced graft polymerization (PIGP) process. Surf. Coat. Technol. 205, 3755–3762 (2011).

  77. 77.

    Totolin, V., Sarmadi, M., Manolache, S. O. & Denes, F. S. Environmentally friendly flame-retardant materials produced by atmospheric pressure plasma modifications. J. Appl. Polym. Sci. 124, 116–122 (2012).

  78. 78.

    Farag, Z. R. et al. Deposition of thick polymer or inorganic layers with flame-retardant properties by combination of plasma and spray processes. Surf. Coat. Technol. 228, 266–274 (2013).

  79. 79.

    Horrocks, A., Eivazi, S., Ayesh, M. & Kandola, B. Environmentally sustainable flame retardant surface treatments for textiles: the potential of a novel atmospheric plasma/UV laser technology. Fibers 6, 31 (2018).

  80. 80.

    Alongi, J. & Malucelli, G. State of the art and perspectives on sol–gel derived hybrid architectures for flame retardancy of textiles. J. Mater. Chem. 22, 21805–21809 (2012).

  81. 81.

    Hench, L. L. & West, J. K. The sol-gel process. Chem. Rev. 90, 33–72 (1990).

  82. 82.

    Esposito, S. “Traditional” sol-gel chemistry as a powerful tool for the preparation of supported metal and metal oxide catalysts. Materials 12, 668 (2019).

  83. 83.

    Hribernik, S. et al. Flame retardant activity of SiO2-coated regenerated cellulose fibres. Polym. Degrad. Stab. 92, 1957–1965 (2007).

  84. 84.

    Alongi, J., Ciobanu, M., Tata, J., Carosio, F. & Malucelli, G. Thermal stability and flame retardancy of polyester, cotton, and relative blend textile fabrics subjected to sol-gel treatments. J. Appl. Polym. Sci. 119, 1961–1969 (2011).

  85. 85.

    Alongi, J., Ciobanu, M. & Malucelli, G. Sol–gel treatments on cotton fabrics for improving thermal and flame stability: Effect of the structure of the alkoxysilane precursor. Carbohydr. Polym. 87, 627–635 (2012).

  86. 86.

    Alongi, J., Ciobanu, M. & Malucelli, G. Thermal stability, flame retardancy and mechanical properties of cotton fabrics treated with inorganic coatings synthesized through sol–gel processes. Carbohydr. Polym. 87, 2093–2099 (2012).

  87. 87.

    Cireli, A. et al. Development of flame retardancy properties of new halogen-free phosphorous doped SiO2 thin films on fabrics. J. Appl. Polym. Sci. 105, 3748–3756 (2007).

  88. 88.

    Yaman, N. Preparation and flammability properties of hybrid materials containing phosphorous compounds via sol-gel process. Fibers Polym. 10, 413–418 (2009).

  89. 89.

    Alongi, J., Ciobanu, M. & Malucelli, G. Novel flame retardant finishing systems for cotton fabrics based on phosphorus-containing compounds and silica derived from sol–gel processes. Carbohydr. Polym. 85, 599–608 (2011).

  90. 90.

    Brancatelli, G., Colleoni, C., Massafra, M. R. & Rosace, G. Effect of hybrid phosphorus-doped silica thin films produced by sol-gel method on the thermal behavior of cotton fabrics. Polym. Degrad. Stab. 96, 483–490 (2011).

  91. 91.

    Cheng, X.-W., Liang, C.-X., Guan, J.-P., Yang, X.-H. & Tang, R.-C. Flame retardant and hydrophobic properties of novel sol-gel derived phytic acid/silica hybrid organic-inorganic coatings for silk fabric. Appl. Surf. Sci. 427, 69–80 (2018).

  92. 92.

    Grancaric, A. M., Colleoni, C., Guido, E., Botteri, L. & Rosace, G. Thermal behaviour and flame retardancy of monoethanolamine-doped sol-gel coatings of cotton fabric. Prog. Org. Coat. 103, 174–181 (2017).

  93. 93.

    Nie, S., Jin, D., Yang, J., Dai, G. & Luo, Y. Fabrication of environmentally-benign flame retardant cotton fabrics with hydrophobicity by a facile chemical modification. Cellulose 26, 5147–5158 (2019).

  94. 94.

    Vasiljević, J. et al. Study of flame-retardant finishing of cellulose fibres: organic–inorganic hybrid versus conventional organophosphonate. Polym. Degrad. Stab. 98, 2602–2608 (2013).

  95. 95.

    Liu, Y. et al. Effect of phosphorus-containing inorganic-organic hybrid coating on the flammability of cotton fabrics: synthesis, characterization and flammability. Chem. Eng. J. 294, 167–175 (2016).

  96. 96.

    Jiang, Z. et al. Flame retardancy and thermal behavior of cotton fabrics based on a novel phosphorus-containing siloxane. Appl. Surf. Sci. 479, 765–775 (2019).

  97. 97.

    Castellano, A. et al. Synthesis and characterization of a phosphorous/nitrogen based sol-gel coating as a novel halogen- and formaldehyde-free flame retardant finishing for cotton fabric. Polym. Degrad. Stab. 162, 148–159 (2019).

  98. 98.

    Alongi, J., Ciobanu, M. & Malucelli, G. Cotton fabrics treated with hybrid organic–inorganic coatings obtained through dual-cure processes. Cellulose 18, 1335–1348 (2011).

  99. 99.

    Vasiljevic, J. et al. Multifunctional superhydrophobic/oleophobic and flame-retardant cellulose fibres with improved ice-releasing properties and passive antibacterial activity prepared via the sol–gel method. J. Sol-Gel Sci. Technol. 70, 385–399 (2014).

  100. 100.

    Šehić, A. et al. Synergistic inhibitory action of P- and Si-containing precursors in sol–gel coatings on the thermal degradation of polyamide 6. Polym. Degrad. Stab. 128, 245–252 (2016).

  101. 101.

    Qin, H., Li, X., Zhang, X. & Guo, Z. Preparation and performance testing of superhydrophobic flame retardant cotton fabric. N. J. Chem. 43, 5839–5848 (2019).

  102. 102.

    Wang, Y. & Zhao, J. Benign design and the evaluation of pyrolysis kinetics of polyester resin based intumescent system comprising of alkali-activated silica fume. Prog. Org. Coat. 122, 30–37 (2018).

  103. 103.

    Wang, Y. & Zhao, J. Comparative study on flame retardancy of silica fume-based geopolymer activated by different activators. J. Alloy. Compd. 743, 108–114 (2018).

  104. 104.

    Bentis, A. et al. Flammability and combustion behavior of cotton fabrics treated by the sol gel method using ionic liquids combined with different anions. Cellulose 26, 2139–2153 (2019).

  105. 105.

    Decher, G. & Hong, J. D. Buildup of ultrathin multilayer films by a self-assembly process: II. consecutive adsorption of anionic and cationic bipolar amphiphiles and polyelectrolytes on charged surfaces. Ber. Bunsenges. Phys. Chem. 95, 1430–1434 (1991).

  106. 106.

    Decher, G. & Schlenoff, J. B. Multilayer Thin Films: Sequential Assembly of Nanocomposite Materials 2nd edn (Wiley, 2012).

  107. 107.

    Cain, A. A., Nolen, C. R., Li, Y.-C., Davis, R. & Grunlan, J. C. Phosphorous-filled nanobrick wall multilayer thin film eliminates polyurethane melt dripping and reduces heat release associated with fire. Polym. Degrad. Stab. 98, 2645–2652 (2013).

  108. 108.

    Li, Y.-C., Kim, Y. S., Shields, J. & Davis, R. Controlling polyurethane foam flammability and mechanical behaviour by tailoring the composition of clay-based multilayer nanocoatings. J. Mater. Chem. A 1, 12987–12997 (2013).

  109. 109.

    Kim, Y. S. & Davis, R. Multi-walled carbon nanotube layer-by-layer coatings with a trilayer structure to reduce foam flammability. Thin Solid Films 550, 184–189 (2014).

  110. 110.

    Pan, H. et al. Synergistic effect of layer-by-layer assembled thin films based on clay and carbon nanotubes to reduce the flammability of flexible polyurethane foam. Ind. Eng. Chem. Res. 53, 14315–14321 (2014).

  111. 111.

    Yang, Y.-H., Li, Y.-C., Shields, J. & Davis, R. D. Layer double hydroxide and sodium montmorillonite multilayer coatings for the flammability reduction of flexible polyurethane foams. J. Appl. Polym. Sci. 132, 41767 (2015).

  112. 112.

    Zhang, X., Shen, Q., Zhang, X., Pan, H. & Lu, Y. Graphene oxide-filled multilayer coating to improve flame-retardant and smoke suppression properties of flexible polyurethane foam. J. Mater. Sci. 51, 10361–10374 (2016).

  113. 113.

    Pan, H., Lu, Y., Song, L., Zhang, X. & Hu, Y. Construction of layer-by-layer coating based on graphene oxide/β-FeOOH nanorods and its synergistic effect on improving flame retardancy of flexible polyurethane foam. Compos. Sci. Technol. 129, 116–122 (2016).

  114. 114.

    Li, Y.-C., Yang, Y.-H., Kim, Y. S., Shields, J. & Davis, R. D. DNA-based nanocomposite biocoatings for fire-retarding polyurethane foam. Green Mater. 2, 144–152 (2014).

  115. 115.

    Liu, X. et al. Combination intumescent and kaolin-filled multilayer nanocoatings that reduce polyurethane flammability. Macromol. Mater. Eng. 304, 1800531 (2019).

  116. 116.

    Carosio, F., Di Blasio, A., Cuttica, F., Alongi, J. & Malucelli, G. Self-assembled hybrid nanoarchitectures deposited on poly(urethane) foams capable of chemically adapting to extreme heat. RSC Adv. 4, 16674–16680 (2014).

  117. 117.

    Alongi, J., Carosio, F. & Malucelli, G. Influence of ammonium polyphosphate-/poly(acrylic acid)-based layer by layer architectures on the char formation in cotton, polyester and their blends. Polym. Degrad. Stab. 97, 1644–1653 (2012).

  118. 118.

    Kumar Kundu, C. et al. A green approach to constructing multilayered nanocoating for flame retardant treatment of polyamide 66 fabric from chitosan and sodium alginate. Carbohydr. Polym. 166, 131–138 (2017).

  119. 119.

    Zanetti, M., Kashiwagi, T., Falqui, L. & Camino, G. Cone calorimeter combustion and gasification studies of polymer layered silicate nanocomposites. Chem. Mater. 14, 881–887 (2002).

  120. 120.

    Li, Y.-C., Schulz, J. & Grunlan, J. C. Polyelectrolyte/nanosilicate thin-film assemblies: influence of pH on growth, mechanical behavior, and flammability. ACS Appl. Mater. Interfaces 1, 2338–2347 (2009).

  121. 121.

    Li, Y.-C. et al. Flame retardant behavior of polyelectrolyte−clay thin film assemblies on cotton fabric. ACS Nano 4, 3325–3337 (2010).

  122. 122.

    Choi, K., Seo, S., Kwon, H., Kim, D. & Park, Y. T. Fire protection behavior of layer-by-layer assembled starch–clay multilayers on cotton fabric. J. Mater. Sci. 53, 11433–11443 (2018).

  123. 123.

    Huang, G., Yang, J., Gao, J. & Wang, X. Thin films of intumescent flame retardant-polyacrylamide and exfoliated graphene oxide fabricated via layer-by-layer assembly for improving flame retardant properties of cotton fabric. Ind. Eng. Chem. Res. 51, 12355–12366 (2012).

  124. 124.

    Ding, X. et al. Carbon nanotube-filled intumescent multilayer nanocoating on cotton fabric for enhancing flame retardant property. Surf. Coat. Technol. 305, 184–191 (2016).

  125. 125.

    Pan, H. et al. Construction of layer-by-layer assembled chitosan/titanate nanotubes based nanocoating on cotton fabrics: flame retardant performance and combustion behavior. Cellulose 22, 911–923 (2015).

  126. 126.

    Uğur, Ş. S., Sarıışık, M. & Aktaş, A. H. Nano-Al2O3 multilayer film deposition on cotton fabrics by layer-by-layer deposition method. Mater. Res. Bull. 46, 1202–1206 (2011).

  127. 127.

    Kandola, B. K., Horrocks, A. R., Price, D. & Coleman, G. V. Flame-retardant treatments of cellulose and their influence on the mechanism of cellulose pyrolysis. J. Macromol. Sci. C Polym. Rev. 36, 721–794 (1996).

  128. 128.

    Li, Y.-C. et al. Intumescent all-polymer multilayer nanocoating capable of extinguishing flame on fabric. Adv. Mater. 23, 3926–3931 (2011).

  129. 129.

    Kim, Y. S., Davis, R., Cain, A. A. & Grunlan, J. C. Development of layer-by-layer assembled carbon nanofiber-filled coatings to reduce polyurethane foam flammability. Polymer 52, 2847–2855 (2011).

  130. 130.

    Cain, A. A. et al. Iron-containing, high aspect ratio clay as nanoarmor that imparts substantial thermal/flame protection to polyurethane with a single electrostatically-deposited bilayer. J. Mater. Chem. A 2, 17609–17617 (2014).

  131. 131.

    Zhang, C., Milhorn, A., Haile, M., Mai, G. & Grunlan, J. C. Nanocoating of starch and clay that reduces the flammability of polyurethane foam. Green Mater. 5, 182–186 (2017).

  132. 132.

    Laufer, G., Kirkland, C., Cain, A. A. & Grunlan, J. C. Clay–chitosan nanobrick walls: completely renewable gas barrier and flame-retardant nanocoatings. ACS Appl. Mater. Interfaces 4, 1643–1649 (2012).

  133. 133.

    Qin, S. et al. Super gas barrier and fire resistance of nanoplatelet/nanofibril multilayer thin films. Adv. Mater. Interfaces 6, 1801424 (2019).

  134. 134.

    Pan, H. et al. Comparative study of layer by layer assembled multilayer films based on graphene oxide and reduced graphene oxide on flexible polyurethane foam: flame retardant and smoke suppression properties. RSC Adv. 6, 114304–114312 (2016).

  135. 135.

    Maddalena, L., Carosio, F., Gomez, J., Saracco, G. & Fina, A. Layer-by-layer assembly of efficient flame retardant coatings based on high aspect ratio graphene oxide and chitosan capable of preventing ignition of PU foam. Polym. Degrad. Stab. 152, 1–9 (2018).

  136. 136.

    Zhang, T. et al. Construction of flame retardant nanocoating on ramie fabric via layer-by-layer assembly of carbon nanotube and ammonium polyphosphate. Nanoscale 5, 3013–3021 (2013).

  137. 137.

    Holder, K. M. et al. Carbon nanotube multilayer nanocoatings prevent flame spread on flexible polyurethane foam. Macromol. Mater. Eng. 301, 665–673 (2016).

  138. 138.

    Pan, H. et al. Formation of layer-by-layer assembled titanate nanotubes filled coating on flexible polyurethane foam with improved flame retardant and smoke suppression properties. ACS Appl. Mater. Interfaces 7, 101–111 (2015).

  139. 139.

    Pan, H., Shen, Q., Zhang, Z., Yu, B. & Lu, Y. MoS2-filled coating on flexible polyurethane foam via layer-by-layer assembly technique: flame-retardant and smoke suppression properties. J. Mater. Sci. 53, 9340–9349 (2018).

  140. 140.

    Lazar, S. et al. Extreme heat shielding of clay/chitosan nanobrick wall on flexible foam. ACS Appl. Mater. Interfaces 10, 31686–31696 (2018).

  141. 141.

    Patra, D. et al. Inorganic nanoparticle thin film that suppresses flammability of polyurethane with only a single electrostatically-assembled bilayer. ACS Appl. Mater. Interfaces 6, 16903–16908 (2014).

  142. 142.

    Mu, X. et al. A single α-cobalt hydroxide/sodium alginate bilayer layer-by-layer assembly for conferring flame retardancy to flexible polyurethane foams. Mater. Chem. Phys. 191, 52–61 (2017).

  143. 143.

    Haile, M., Fomete, S., Lopez, I. D. & Grunlan, J. C. Aluminum hydroxide multilayer assembly capable of extinguishing flame on polyurethane foam. J. Mater. Sci. 51, 375–381 (2016).

  144. 144.

    Shi, X. et al. Bi-phase fire-resistant polyethylenimine/graphene oxide/melanin coatings using layer by layer assembly technique: smoke suppression and thermal stability of flexible polyurethane foams. Polymer 170, 65–75 (2019).

  145. 145.

    Carosio, F. & Fina, A. Three organic/inorganic nanolayers on flexible foam allow retaining superior flame retardancy performance upon mechanical compression cycles. Front. Mater. 6, 20 (2019).

  146. 146.

    Pan, Y. et al. Effect of layer-by-layer self-assembled sepiolite-based nanocoating on flame retardant and smoke suppressant properties of flexible polyurethane foam. Appl. Clay Sci. 168, 230–236 (2019).

  147. 147.

    Carosio, F., Negrell-Guirao, C., Alongi, J., David, G. & Camino, G. All-polymer layer by layer coating as efficient solution to polyurethane foam flame retardancy. Eur. Polym. J. 70, 94–103 (2015).

  148. 148.

    Carosio, F., Ghanadpour, M., Alongi, J. & Wågberg, L. Layer-by-layer-assembled chitosan/phosphorylated cellulose nanofibrils as a bio-based and flame protecting nano-exoskeleton on PU foams. Carbohydr. Polym. 202, 479–487 (2018).

  149. 149.

    Wang, X., Pan, Y.-T., Wan, J.-T. & Wang, D.-Y. An eco-friendly way to fire retardant flexible polyurethane foam: layer-by-layer assembly of fully bio-based substances. RSC Adv. 4, 46164–46169 (2014).

  150. 150.

    Laufer, G., Kirkland, C., Morgan, A. B. & Grunlan, J. C. Exceptionally flame retardant sulfur-based multilayer nanocoating for polyurethane prepared from aqueous polyelectrolyte solutions. ACS Macro Lett. 2, 361–365 (2013).

  151. 151.

    Jimenez, M. et al. Microintumescent mechanism of flame-retardant water-based chitosan-ammonium polyphosphate multilayer nanocoating on cotton fabric. J. Appl. Polym. Sci. 133, (2016).

  152. 152.

    Laufer, G., Kirkland, C., Morgan, A. B. & Grunlan, J. C. Intumescent multilayer nanocoating, made with renewable polyelectrolytes, for flame-retardant cotton. Biomacromolecules 13, 2843–2848 (2012).

  153. 153.

    Zhang, T., Yan, H., Wang, L. & Fang, Z. Controlled formation of self-extinguishing intumescent coating on ramie fabric via layer-by-layer assembly. Ind. Eng. Chem. Res. 52, 6138–6146 (2013).

  154. 154.

    Fang, F. et al. Intumescent flame retardant coatings on cotton fabric of chitosan and ammonium polyphosphate via layer-by-layer assembly. Surf. Coat. Technol. 262, 9–14 (2015).

  155. 155.

    Alongi, J. et al. DNA: a novel, green, natural flame retardant and suppressant for cotton. J. Mater. Chem. A 1, 4779–4785 (2013).

  156. 156.

    Pan, H. et al. Layer-by-layer assembled thin films based on fully biobased polysaccharides: chitosan and phosphorylated cellulose for flame-retardant cotton fabric. Cellulose 21, 2995–3006 (2014).

  157. 157.

    Pan, H. et al. Formation of self-extinguishing flame retardant biobased coating on cotton fabrics via layer-by-layer assembly of chitin derivatives. Carbohydr. Polym. 115, 516–524 (2015).

  158. 158.

    Wang, L., Zhang, T., Yan, H., Peng, M. & Fang, Z. Modification of ramie fabric with a metal-ion-doped flame-retardant coating. J. Appl. Polym. Sci. 129, 2986–2997 (2013).

  159. 159.

    Yan, H., Zhao, L., Fang, Z. & Wang, H. Construction of multilayer coatings for flame retardancy of ramie fabric using layer-by-layer assembly: article. J. Appl. Polym. Sci. 134, 45556 (2017).

  160. 160.

    Liu, Y. et al. Effect of chitosan on the fire retardancy and thermal degradation properties of coated cotton fabrics with sodium phytate and APTES by LBL assembly. J. Anal. Appl. Pyrolysis 135, 289–298 (2018).

  161. 161.

    Li, S. et al. Phosphorus-nitrogen-silicon-based assembly multilayer coating for the preparation of flame retardant and antimicrobial cotton fabric. Cellulose 26, 4213–4223 (2019).

  162. 162.

    Huang, G., Liang, H., Wang, X. & Gao, J. Poly(acrylic acid)/clay thin films assembled by layer-by-layer deposition for improving the flame retardancy properties of cotton. Ind. Eng. Chem. Res. 51, 12299–12309 (2012).

  163. 163.

    Jiang, S.-D. et al. Synthesis of mesoporous silica@Co–Al layered double hydroxide spheres: layer-by-layer method and their effects on the flame retardancy of epoxy resins. ACS Appl. Mater. Interfaces 6, 14076–14086 (2014).

  164. 164.

    Xuan, H., Ren, J., Wang, X., Zhang, J. & Ge, L. Flame-retardant, non-irritating and self-healing multilayer films with double-network structure. Compos. Sci. Technol. 145, 15–23 (2017).

  165. 165.

    Liu, L. et al. Layer-by-layer assembly of hypophosphorous acid-modified chitosan based coating for flame-retardant polyester–cotton blends. Ind. Eng. Chem. Res. 56, 9429–9436 (2017).

  166. 166.

    Fang, F. et al. Boron-containing intumescent multilayer nanocoating for extinguishing flame on cotton fabric. Cellulose 23, 2161–2172 (2016).

  167. 167.

    Alongi, J., Carosio, F. & Malucelli, G. Layer by layer complex architectures based on ammonium polyphosphate, chitosan and silica on polyester-cotton blends: flammability and combustion behaviour. Cellulose 19, 1041–1050 (2012).

  168. 168.

    Carosio, F., Alongi, J. & Malucelli, G. Layer by layer ammonium polyphosphate-based coatings for flame retardancy of polyester–cotton blends. Carbohydr. Polym. 88, 1460–1469 (2012).

  169. 169.

    Leistner, M., Abu-Odeh, A. A., Rohmer, S. C. & Grunlan, J. C. Water-based chitosan/melamine polyphosphate multilayer nanocoating that extinguishes fire on polyester-cotton fabric. Carbohydr. Polym. 130, 227–232 (2015).

  170. 170.

    Pan, Y., Liu, L., Wang, X., Song, L. & Hu, Y. Hypophosphorous acid cross-linked layer-by-layer assembly of green polyelectrolytes on polyester-cotton blend fabrics for durable flame-retardant treatment. Carbohydr. Polym. 201, 1–8 (2018).

  171. 171.

    Narkhede, M., Thota, S., Mosurkal, R., Muller, W. S. & Kumar, J. Layer-by-layer assembly of halogen-free polymeric materials on nylon/cotton blend for flame retardant applications: layer-by-layer assembly of halogen-free polymeric materials. Fire Mater. 40, 206–218 (2016).

  172. 172.

    Holder, K. M., Smith, R. J. & Grunlan, J. C. A review of flame retardant nanocoatings prepared using layer-by-layer assembly of polyelectrolytes. J. Mater. Sci. 52, 12923–12959 (2017).

  173. 173.

    Qiu, X., Li, Z., Li, X. & Zhang, Z. Flame retardant coatings prepared using layer by layer assembly: a review. Chem. Eng. J. 334, 108–122 (2018).

  174. 174.

    Richardson, J. J., Bjornmalm, M. & Caruso, F. Technology-driven layer-by-layer assembly of nanofilms. Science 348, aaa2491 (2015).

  175. 175.

    Richardson, J. J. et al. Innovation in layer-by-layer assembly. Chem. Rev. 116, 14828–14867 (2016).

  176. 176.

    Wang, Y. et al. Spray-drying-assisted layer-by-layer assembly of alginate, 3-aminopropyltriethoxysilane, and magnesium hydroxide flame retardant and its catalytic graphitization in ethylene–vinyl acetate resin. ACS Appl. Mater. Interfaces 10, 10490–10500 (2018).

  177. 177.

    Kim, Y. S., Li, Y.-C., Pitts, W. M., Werrel, M. & Davis, R. D. Rapid growing clay coatings to reduce the fire threat of furniture. ACS Appl. Mater. Interfaces 6, 2146–2152 (2014).

  178. 178.

    Mateos, A. J., Cain, A. A. & Grunlan, J. C. Large-scale continuous immersion system for layer-by-layer deposition of flame retardant and conductive nanocoatings on fabric. Ind. Eng. Chem. Res. 53, 6409–6416 (2014).

  179. 179.

    Chang, S., Slopek, R. P., Condon, B. & Grunlan, J. C. Surface coating for flame-retardant behavior of cotton fabric using a continuous layer-by-layer process. Ind. Eng. Chem. Res. 53, 3805–3812 (2014).

  180. 180.

    Apaydin, K. et al. Mechanistic investigation of a flame retardant coating made by layer-by-layer assembly. RSC Adv. 4, 43326–43334 (2014).

  181. 181.

    Carosio, F. et al. Tunable thermal and flame response of phosphonated oligoallylamines layer by layer assemblies on cotton. Carbohydr. Polym. 115, 752–759 (2015).

  182. 182.

    Carosio, F. & Alongi, J. Ultra-fast layer-by-layer approach for depositing flame retardant coatings on flexible PU foams within seconds. ACS Appl. Mater. Interfaces 8, 6315–6319 (2016).

  183. 183.

    Wang, X., Romero, M. Q., Zhang, X.-Q., Wang, R. & Wang, D.-Y. Intumescent multilayer hybrid coating for flame retardant cotton fabrics based on layer-by-layer assembly and sol–gel process. RSC Adv. 5, 10647–10655 (2015).

  184. 184.

    Ren, Y., Huo, T., Qin, Y. & Liu, X. Preparation of flame retardant polyacrylonitrile fabric based on sol-gel and layer-by-layer assembly. Materials 11, 483 (2018).

  185. 185.

    Kundu, C. K., Wang, X., Liu, L., Song, L. & Hu, Y. Few layer deposition and sol-gel finishing of organic-inorganic compounds for improved flame retardant and hydrophilic properties of polyamide 66 textiles: a hybrid approach. Prog. Org. Coat. 129, 318–326 (2019).

  186. 186.

    Cain, A. A., Murray, S., Holder, K. M., Nolen, C. R. & Grunlan, J. C. Intumescent nanocoating extinguishes flame on fabric using aqueous polyelectrolyte complex deposited in single step: intumescent nanocoating extinguishes flame on fabric. Macromol. Mater. Eng. 299, 1180–1187 (2014).

  187. 187.

    Haile, M., Fincher, C., Fomete, S. & Grunlan, J. C. Water-soluble polyelectrolyte complexes that extinguish fire on cotton fabric when deposited as pH-cured nanocoating. Polym. Degrad. Stab. 114, 60–64 (2015).

  188. 188.

    Leistner, M., Haile, M., Rohmer, S., Abu-Odeh, A. & Grunlan, J. C. Water-soluble polyelectrolyte complex nanocoating for flame retardant nylon-cotton fabric. Polym. Degrad. Stab. 122, 1–7 (2015).

  189. 189.

    Haile, M. et al. A wash-durable polyelectrolyte complex that extinguishes flames on polyester–cotton fabric. RSC Adv. 6, 33998–34004 (2016).

  190. 190.

    Cheng, X.-W., Guan, J.-P., Yang, X.-H., Tang, R.-C. & Yao, F. A bio-resourced phytic acid/chitosan polyelectrolyte complex for the flame retardant treatment of wool fabric. J. Clean. Prod. 223, 342–349 (2019).

  191. 191.

    Shi, X.-H. et al. Carbon fibers decorated by polyelectrolyte complexes toward their epoxy resin composites with high fire safety. Chin. J. Polym. Sci. 36, 1375–1384 (2018).

  192. 192.

    Kolibaba, T. J. & Grunlan, J. C. Environmentally benign polyelectrolyte complex that renders wood flame retardant and mechanically strengthened. Macromol. Mater. Eng. 304, 1900179 (2019).

  193. 193.

    Carosio, F. & Alongi, J. Flame retardant multilayered coatings on acrylic fabrics prepared by one-step deposition of chitosan/montmorillonite complexes. Fibers 6, 36 (2018).

  194. 194.

    Schulz, W. G. California revises furniture fire safety standards. C&EN https://cen.acs.org/articles/91/web/2013/11/California-Revises-Furniture-Fire-Safety.html (2013).

  195. 195.

    Evarts, B. Fire Loss in the United States During 2017 (National Fire Protection Agency, 2018).

  196. 196.

    Schartel, B. & Hull, T. R. Development of fire-retarded materials—interpretation of cone calorimeter data. Fire Mater. 31, 327–354 (2007).

  197. 197.

    Huggett, C. Estimation of rate of heat release by means of oxygen consumption measurements. Fire Mater. 4, 61–65 (1980).

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The authors acknowledge the worldwide flame retardant scientific community that provided much of the content herein.

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Correspondence to Jaime C. Grunlan.

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Outright bans on flame retardants: https://chemicalwatch.com/58037/maine-bans-all-flame-retardants-in-upholstered-furniture

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Lazar, S.T., Kolibaba, T.J. & Grunlan, J.C. Flame-retardant surface treatments. Nat Rev Mater 5, 259–275 (2020). https://doi.org/10.1038/s41578-019-0164-6

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