Polysaccharides, in natural or chemically modified form, have become recently increasingly attractive to both research and industrial communities, mainly due to their good solubility in water, high chemical reactivity, and high solution viscosity, at low cost and low toxicity. Among the extensively used chemical modification reactions, oxidation reactions of polysaccharides, represent a promising route to extend the range of applicability since they lead to anionic polyelectrolytes with higher solubility in aqueous media.<br/>In this study, the TEMPO-mediated oxidation of xyloglucan and the subsequent alkylation of the intermediate reaction products using dodecylamine are followed in real time by light scattering-based unique methodologies together with traditional methods. The effects of various factors such as pH, reaction temperature, and polysaccharide structure on the degree of oxidation and on the grafting efficiency and degree of alkylation are investigated. Changes in polymer characteristics (molecular weight distribution, size) during the oxidation reactions and the gradual conversion to polyelectrolyte are illustrated in the evolution of the computed electrostatic and hydrodynamic parameters. Monitoring viscosity and light scattering signatures during both types of reactions offer complementary means to highlight conformational differences between the grafted and starting polymers allowing quantitative assessments to be made about degree of grafting and efficiency of the reactions. It is hoped that the knowledge gained from these studies will offer efficient tools for enhancing targeted material properties.

Chemical modification reactions of polysaccharides studied in real time by light scattering and viscometry-based methods

249th National Meeting (2015)

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