Oxidized xylan additive for nanocellulose films – A swelling modifier

Polymeric wood hemicelluloses are depicted to join cellulose, starch and chitosan as key polysaccharides for sustainable materials engineering. However, the approaches to incorporate hemicelluloses in emerging bio-based products are challenged by lack of specific benefit, other than the biomass-origin, although their utilization would contribute to sustainable material use since they currently are a side stream that is not valorized. Here we demonstrate wood-xylans as swelling modifiers for neutral and charged nanocellulose films that have already entered the sustainable packaging applications, however, suffer from humidity sensitivity. The oxidative modification is used to modulate the water-solubility of xylan and hence enable adsorption in an aqueous environment. A high molecular weight grade, hence less water-soluble, adsorbed preferentially on the neutral surface while the adsorbed amount on a negatively charged surface was independent of the molecular weight, and hence, solubility. The adsorption of the oxidized xylans on a neutral cellulose surface resulted in an increase in the amount of water in the film while on the negatively charged cellulose the total amount of water decreased. The finding of synergy of two hygroscopic materials to decrease swelling in hydrophilic bio-polymer films demonstrates the oxidized macromolecule xylan as structurally functional component in emerging cellulose products.

Publication year: 2021
Authors: Palasingh Ch. a, Ström A. a, Amer H. b,c, Nypelö T. a,d

a – Applied Chemistry, Department of Chemistry and Chemical Engineering, Chalmers University of Technology, 41296 Gothenburg, Sweden
b – Institute of Chemistry of Renewable Resources, Department of Chemistry, University of Natural Resources and Life Sciences, Tulln, Konrad-Lorenz Straße 24, 3430 Tulln, Austria
c – Department of Natural and Microbial Products Chemistry, National Research Centre, 33 AlBohous St., Dokki, Giza, Egypt
d – Wallenberg Wood Science Center, Chalmers University of Technology, Gothenburg, Sweden

Published in: International Journal of Biological Macromolecules, Vol. 180, p. 753-759
DOI: 10.1016/j.ijbiomac.2021.03.062


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