Comparative Analysis of Electrokinetic Properties of Periodate- and TEMPO-Oxidized Regenerated Cellulose Fabric Functionalized with Chitosan

The electrokinetic properties of materials give useful insight into the behavior of surfaces in contact with liquids and other compounds and their quantification is a powerful tool to predict their behavior during further processing and application, especially in textile materials. In this work, we perform a comparative analysis of influence of the two most common selective oxidative protocols for viscose (regenerated cellulose) fabrics on subsequent functionalization with chitosan, and cellulose fabrics’ electrokinetic properties, zeta potential in a pH range of approx. 3–10, and isoelectric point (IEP). For oxidation before deposition of chitosan, sodium periodate and 2,2,6,6-tetramethylpiperidine-1-oxy radical (TEMPO) were used. The content of functional groups in oxidized cellulose fabric (carboxyl and carbonyl groups) was determined by titration methods, while amino functional groups’ availability in samples with chitosan was determined using the CI acid orange 7 dye absorption method. This study reveals that the periodate oxidation (PO) of cellulose is more effective for binding chitosan onto material, which gave rise to higher availability of amino groups onto cellulose/chitosan material, which also influenced the shift in zeta potential curve towards positive values at a pH below 5. Analysis of a relationship between zeta potential increase at pH 4.4 and amino groups’ amount measured using absorption of CI acid orange 7 dye at pH 4.4 revealed dependency that can be fitted linearly or exponentially, with the latter providing the better fit (R2 = 0.75).