Next-Generation Flame Retardant Materials: Design Strategies, Mechanisms, and Future Perspectives

Flame-retardant materials play a crucial role in enhancing fire safety across a wide range of industrial and consumer applications by reducing flammability and slowing fire propagation. This review provides a comprehensive overview of the principal classes of flame-retardant materials and their underlying mechanisms. Although halogenated flame retardants exhibit high fire-suppression efficiency, their adverse effects on human health and the environment have driven a shift toward safer and more sustainable alternatives. Inorganic flame retardants, including aluminium hydroxide and magnesium hydroxide, enhance fire resistance through endothermic decomposition, water release, and the formation of protective barrier layers. Phosphorus- and nitrogen-based systems promote char formation and flame inhibition, with synergistic effects often observed when these elements are combined. More recently, nanostructured flame retardants, such as metal oxides and carbon-based nanomaterials, have emerged as effective additives for improving the thermal stability and fire performance of polymer composites. Additionally, bio-based flame retardants derived from renewable resources—including lignin, starch, chitosan, and phytic acid—have attracted increasing interest due to their sustainability, low toxicity, and promising fire-retardant efficacy. This review also covers how flame retardants are used in different materials such as thermoplastics, epoxy resins, textiles, and wood products. It highlights new trends like nano-engineered systems that offer multiple benefits. These benefits include fire resistance, durability, and recyclability. While reducing smoke and harmful gases. Growing research is focused on creating low-toxicity, sustainable, and recyclable flame-retardant systems that meet safety standards. Finally, the review points out the importance of reducing toxicity and pollution risks, calling for continued efforts to develop cleaner and safer flame-retardant technologies.