Water-soluble quaternized copolymers as eco-friendly cationic modifiers of cotton fabrics for salt-free reactive dyeing applications

Abstract The modification of cotton fabrics with water-soluble cationic copolymers for salt-free dyeing applications with reactive dyes is explored in the present work. To this end, a family of bifunctional water-soluble cationic copolymers was designed through the chemical modification of poly(4-vinyl benzyl chloride), PVBC, with triethylamine, TEAM. These copolymers were applied onto cotton fabrics in aqueous alkaline solutions at moderate temperature (60 °C). The successful cotton modification was verified through the characterization of the modified samples with Raman and XPS spectroscopy. Moreover, a polymer coverage of the fabric of the order of 0.1% (w/w) was estimated following the polymer exhaustion through UV–Vis spectroscopy of the aqueous solutions used for the modification. The modification kinetics were followed through the evolution of the Raman spectra of the modified fabrics, the polymer exhaustion of the aqueous modification solutions and, indirectly, the dye exhaustion of the dyebaths using a reactive dye, namely Novacron Ruby S-3B. All techniques claim that fabric modification is practically accomplished within the first 1–2 h. The double functionality of the copolymers was explored through the XPS study of the modified fabrics, revealing that both electrostatic binding and covalent bonding of the cationic copolymers with the anionic surface of the fabric are expected to take place. As an important consequence, the polymer-modified fabrics are strongly dyed under eco-friendlier conditions, namely in salt-free alkaline solutions at room temperature, in contrast to the barely dyed unmodified fabric. Graphical abstract