Relationship between wettability of cotton and dyeing properties of reactive dyes in a non‐aqueous medium system

Abstract Herein, we initially used sodium hydroxide to pretreat cotton fabric to obtain different wettability. Then the non‐aqueous dyeing system was applied to the eco‐friendly dyeing and washing process of cotton fibre. Meanwhile, Fourier‐transform infrared (FTIR) spectrometry and zeta potential analysis were performed to analyse the difference of cotton fibres before and after pretreatment. Furthermore, the effect of pretreatment on the adsorption behaviour was investigated by molecular dynamic (MD) simulations. Compared with control cotton, an approximate increase of 23.0% in the colour strength ( K/S ) value was achieved. Findings from FTIR and zeta potential showed that the number of available hydroxyl groups of cotton involved in the dyeing increased after pretreatment. MD simulations demonstrated reactive dye molecules showed a faster adsorption behaviour on the fibre surface with good wettability. It was attributed to the increased interaction energy between dye molecules and cotton fibres. Therefore, improving the cotton fabric's wettability is an effective way to improve the utilisation rate of reactive dyes in a non‐aqueous medium dyeing system.