# Metal-Organic Frameworks as Promising Textile Flame Retardants: Importance and Application Methods
## 1 Introduction  
The textile chain is responsible for transforming fibers and filaments into structures such as woven, knitted, and nonwoven fabrics. Known for its importance in satisfying the human need for clothing, the textile industry is capable of innovating processes and products to meet specific demands, ranging from providing new tactile and visual characteristics to developing intelligent fabrics that improve quality of life. Textile finishing, a sector at the end of the textile chain, is responsible for this function of emboking the fabric, i.e., improving existing characteristics or providing new functions. In short, finishing processes tend to satisfy the interests of consumers who are looking for ways to combine practicality, protection, aesthetics, and other factors in a single product. The textile chain tends to develop innovative products with a variety of functions in proportion to market demand. With the advent of nanotechnology, various transformations and changes in human daily life have occurred, and in the same way, textile chemical finishes have followed this evolution. In recent years, increased research on nanoparticles has led to the production of textiles with greater efficiency and added value [1]. Water and oil repellency, stain repellency, self-cleaning, wrinkle resistance, flame retardancy, UV protection, antistatic properties, and better dyeability are some of the functionalities obtained using nanomaterials and nanofibers [2]. The functionalization of these finishes can be achieved by coating or impregnation processes using emulsions, microemulsions, nanoparticles, nanocomposites, and other products. Like any anthropogenic activity, textile finishing has an impact on the environment due to the high consumption of water, the generation of physical and chemical waste, and the emission of gases of different classes, most of which are harmful. Therefore, the industry is trying to overcome the challenges of sustainability in the textile process when developing products. The constant search for solutions to these challenges leads to the development of new processes and products that combine innovation with sustainable cooperation. Textile materials with exceptional functionality are defined as functional textiles [2]. One of the functionalities obtained by finishing is flame retardancy, which is a relevant class of finishes due to its importance in the composition of protective articles, such as military uniforms and the covering of fire-prone areas. These flame retardant finishes can be applied both in the manufacture of the yarn or fiber and in the textile structure, both of which must inhibit or suppress the combustion process when exposed to fire or high temperatures. These compounds applied to textiles, called flame retardants (FRs), can slow the spread of flames through physical or chemical action [3]. In turn, there are already products on the market capable of reducing flammability and delaying fire. Although widely used and highly effective, some molecular compounds used in the formulation of halogen-based flame retardants, such as pentabromodiphenyl ether, decabromodiphenyl ether (or oxide), and polychlorinated biphenyls, have been shown to be bioaccumulative and/or environmentally toxic to animals and humans [4]. Due to the prohibition and limitation of the use of halogenated flame retardants (FRs), the market has been encouraged to develop alternatives with greater stability and lower volatility. To meet the environmental safety requirements of FRs, the development of new halogen-free FRs has become inevitable. In recent years, metal-organic frameworks (MOFs) have emerged as a promising class of flame retardants, as they can be synthesized with different metal ions and organic ligands, allowing for the modulation of their properties for specific applications. This chemical flexibility enables the design of highly customized flame retardants, which are optimized for different types of materials and operating conditions.