Spectroscopic study of interactions between model direct dyes and cotton

Abstract

Although examined for years, interactions between direct dyes and the chemical structure of cotton cellulose remain an interesting, and still not entirely known, chemical phenomenon occurring in the fiber. Ten model azo dyes have been studied in aqueous solution, as dye powders and on cotton fabric using 13C MAS NMR and UV-visible spectroscopy. NMR spectroscopy indicates that model azo dyes, especially dye 8, interact by μ-stacking at the central biphenyl group, and that there is hydrogen bonding with cellulose. Model azo dyes are present as the azo or hydrazone tautomer. The UV-visible λmax indicate that shifts are attributed to adsorption of model azo dyes into cellulose surfaces. © 2007 Wiley Periodicals, Inc.