Two-step, single-cycle coating of montmorillonite/PEG/PEI on cellulosic polysaccharide fabrics: Enhanced flame retardancy and thermal stability.

Abstract

Cotton fabrics composed of cellulosic polysaccharides are highly flammable, creating a need for effective flame-retardant treatments. Conventional layer-by-layer (LbL) assembly can improve fire resistance but requires repeated deposition and rinsing steps, resulting in high water and energy consumption. In this study, a two-step coating process based on montmorillonite (MMT), polyethylene glycol (PEG), and polyethyleneimine (PEI) was applied to cellulose-based fabrics. The coating procedure consisted of PEI pretreatment followed by application of an MMT/PEG dispersion and drying at 80 °C. The effects of PEG molecular weight and MMT content on flame-retardant performance were investigated. SEM/EDS and FT-IR analyses indicated the formation of a continuous coating layer on the fiber surface, while thermogravimetric analysis showed increased char formation and improved thermal stability after treatment. Vertical flame testing demonstrated improved resistance to flame propagation compared with untreated cotton fabrics. The MMT/PEG dispersion was prepared by stirring for 24 h before use, whereas the fabric coating and drying procedure required approximately 80 min. Compared with conventional multilayer LbL assembly, which requires repeated deposition, rinsing, and drying cycles, the proposed process reduced the number of treatment steps. The results indicate that the MMT/PEG/PEI coating system can improve the fire performance of cellulosic fabrics through a simplified coating process.