Self-healing films based on chitosan containing citric acid/choline chloride deep eutectic solvent

• Published in: Polymer testing 2021-05, Vol.97, p.107156, Article 107156
• Main Authors: Smirnov, Michael A., Nikolaeva, Alexandra L., Bobrova, Natalia V., Vorobiov, Vitaly K., Smirnov, Alexander V., Lahderanta, Erkki, Sokolova, Maria P.
• Format: Article
• Language: English
• Subjects: Chitosan; Choline chloride; Citric acid; Deep eutectic solvents; Polymer actuator; Self-healing
• ISSN: 0142-9418; 1873-2348
• DOI: 10.1016/j.polymertesting.2021.107156

Plasticized chitosan films with high content (67–82 wt%) of natural deep eutectic solvent (NADES) based on citric acid and choline chloride were prepared by solution casting method. The thickness of films was 19 ± 3 μm. The self-healing and water vapor bending movement of prepared films were demonstrated. Maximal mechanical characteristics of 84% elongation at break and 18 MPa strength, were achieved for a film containing 67 wt% of NADES. The formation of hydrogen bond network in the chitosan film due to replacement of citric acid with NADES (citric acid/choline chloride) was observed with FTIR. It is proposed that this network is responsible for self-healing ability of the chitosan–citric acid–choline chloride films. Structure, morphology and thermal properties of the prepared films are also discussed. •Chitosan (CS) was plasticized with citric acid/choline chloride (NADES).•Maximal elasticity for film with 67 wt% of NADES was found.•Self-healing ability of fully bio-based elastic CS/NADES film was demonstrated.•CS/NADES film shows fast and reversible water vapor-induced movement.•High NADES content (75 and 82 wt%) leads to inhomogeneity of films' structure.