Clay Nanotube Coating on Cotton Fibers for Enhanced Flame‐Retardancy and Antibacterial Properties

Abstract Cotton and its blends are among the most common textiles used. Although cotton is a highly flammable material, its flammability may be reduced with a retardant coating. We developed an architectural build of organic/inorganic coating with layer‐by‐layer (LbL) assembly of the cationic polyethyleneimine (PEI) and anionic halloysite clay nanotubes (HNT) on raw cotton. The biocompatible SiO₂/Al₂O₃ HNTs have a 50‐nm diameter hollow structure that can carry chemicals and ensures safe interactions of treated textiles with living organisms. The treated cotton was characterized using TGA, SEM, TEM, and IR spectroscopy for optimization of the finishing process. The nanoclay‐coated cotton was burned to determine the extent of fire protection and resulted in the flame self‐extinguishing. Adding only two bilayers of PEI/HNT coating, which accounted for ca 7 wt.% of the tissue, was shown to give an optimal level of flame retardancy to the processed cotton; further nanoclay layering increased flame retardancy at a diminishing rate and may not be necessary in industrial processes. These clay nanotubes were also loaded with color‐enhancing dyes, antimicrobial chloramphenicol or silver, providing architectural coatings with complex functionality. This proposed green technology combines natural cotton fibers, and abundantly available halloysite clay in this new nanocomposite textile product.