Ionic liquid-regenerated cellulose–chitosan coatings: A Bio-based coating for enhancing paper packaging performance

This study explores the development of eco-friendly paper coatings using regenerated cellulose dissolved in the ionic liquid 1-ethyl-3-methylimidazoliun acetate, with modifications by chitosan and citric acid crosslinking. The coatings were applied to one side of paper substrates, and their thermal stability, mechanical properties, surface morphology, wettability, and barrier performance were systematically evaluated. A notable enhancement in mechanical strength was achieved, as the tensile strength increased from 8.35 ± 0.39 MPa for the uncoated paper to 14.20 ± 0.29 MPa in the citric acid–crosslinked coatings. The coatings also significantly improved performance, achieving a water vapor permeability as low as (11.0 ± 0.32) × 10^–5 g/m/d/Pa in the citric acid–crosslinked samples and a char yield of 13.4 % at 700 °C in the citric acid crosslinked cellulose/chitosan coatings. Chitosan enhanced the mechanical properties, likely due to hydrogen bonding between chitosan and cellulose chains. However, it slightly decreased elongation at break compared to the pure cellulose coating, likely owing to increased rigidity. Citric acid crosslinking contributed to a denser network structure, further improving tensile strength and thermal stability. Nevertheless, the combination of citric acid and chitosan appeared to increase rigidity excessively, resulting in moderate overall mechanical and barrier properties. Crown Copyright © 2025 Published by Elsevier B.V.