Fabrication of Sustainable Hydrophobic Cotton Fabrics with Fluorescence-Emitting Performance Using Novel 1,8-Naphthalimide Functional Molecules

Cotton fabrics with high value fluorescent and hydrophobic properties are highly needed in the functional textile industry. A facile method of imparting fluorescent and hydrophobic characteristics to cotton fabrics was developed through the application of novel fluorescent molecules in this work. Three 1,8-naphthalimide fluorescent dyes (FH1, FH2, FH3) with carboxyl reactive groups and different lengths of aliphatic carbon chains were synthesized and characterized first. The N,N-carbamide diimidazole-catalyzed esterification reaction was employed to fix fluorescent dyes covalently on the cotton fabrics. The morphologies and microstructures of the functional fabrics were characterized. The apparent color, fluorescence emissions, and hydrophobic properties of the three molecule-modified fabrics were investigated and compared. The FH3-modified fabric exhibited strong yellow-green fluorescence and achieved a water contact angle of 127°, being outstanding in separating hydrocarbons from water. The hydrophobic performance originated from the hydrophobic layer formed on the surface of the fabric by the long carbon chain was verified by theoretical calculations. This way of constructing fluorescent and hydrophobic cotton fabrics is promising in green and functional textile manufacturing without using fluorine compounds and complex preparation processes.