Flame Retarded Cotton Fabrics: Current Achievements, Open Challenges, and Future Perspectives

Among cellulosic textiles, cotton is the most utilized, thanks to its peculiar charac- teristics (including softness, hygroscopicity, excellent breathability, comfortable- ness, biodegradation, and good thermal conductivity, among a few to mention). However, cotton burns very easily when it comes in contact with a flame or is exposed to an irradiative heat flux: as a consequence, this negative effect remark- ably confines the possible exploitation of this material, particularly referring to those application sectors where flame retardant fibers and fabrics are a prerequi- site. In this context, the academic and industrial work has been extensively focused on improving the flame retardant behavior of this cellulosic material. Among the different possible solutions, the so-called surface engineering represents a suit- able and efficient strategy for conferring flame retardant properties to cotton: in fact, this approach allows the deposition of fully inorganic, fully organic, or hybrid organic–inorganic protective coatings on the fiber/fabric surface. In doing so, the heat and mass transfer phenomena occurring during the fire stages can be remark- ably limited: in particular, the structure and composition of the deposited coatings play a key role in the formation of a protective layer on the textile substrate, thus conferring the envisaged flame retardant properties to this latter. From an over- all point of view, the surface engineering approaches mainly involve sol–gel pro- cesses and layer-by-layer architectures. In particular, the sol–gel technique, which is a very well consolidated approach for the fabrication of ceramics, has started to be exploited also in the textile field because of its advantageous characteristics: among them, it is easily applicable to even irregular substrates as fibers and fabrics, it can be carried out using the already existing industrial finishing lines (such as impregnation/exhaustion units), and it is very efficient in providing the treated substrates with flame retardant features. Besides, the layer-by-layer approach, though it has been well established practically at a lab-scale only, shows some interesting potentialities in a view of a possible scale-up. In addition, very often, the aforementioned techniques allow providing the processed fibers/fabrics with more than one functionality: more specifically, the scientific literature well high- lights the possibility of conferring antibacterial/antimicrobial features, low surface tension, and electrical conductivity, apart from the flame retardant properties. Finally, sol–gel and, sometimes, layer-by-layer architectures (the latter depending on the presence of reactive functional groups in the deposited assemblies, which can permanently link the layers to the fabric substrate) can ensure washing fast- ness to the treated fabrics, which is very often a requisite for a wide number of applications. This chapter aims to review the state of the art and the still open challenges related to the design of effective flame retarded cotton fabrics. In particular, the current achievements in flame retardancy, specifically involving nanotechnology and surface engineering, will be thoroughly described, highlighting the present limitations and some possible further improvements.