Bio-inspired films based on chitosan, nanoclays and cellulose nanocrystals: structuring and properties improvement by using water-evaporation-induced self-assembly

• Published in: Cellulose (London) 2019-01, Vol.26 (4), p.2389-2401
• Main Authors: Enescu, Daniela, Gardrat, Christian, Cramail, Henri, Le Coz, Cédric, Sèbe, Gilles, Coma, Véronique
• Format: Article
• Language: English
• Subjects: Bioorganic Chemistry; Cellulose; Ceramics; Chemical Sciences; Chemistry; Chemistry and Materials Science; Chitosan; Composites; Diffusion rate; Evaporation; Glass; Mechanical properties; Modulus of elasticity; Nacre; Nanocrystals; Natural Materials; Organic Chemistry; Original Research; Physical Chemistry; Platelets; Polymer Sciences; Polymers; Self-assembly; Sustainable Development; Synergistic effect; Thermal stability; Water vapor; Weight
• ISSN: 0969-0239; 1572-882X
• DOI: 10.1007/s10570-018-2211-7

Herein, we report a novel approach for the preparation of chitosan films with improved mechanical and barrier properties, by incorporating a mixture of nanoclays (MMT) and cellulose nanocrystals (CNC), via a water-evaporation-induced self-assembly process. The improvements obtained were assigned to: (1) the slow evaporation of water, leading to nacre-like structures; (2) a synergistic effect created between MMT and CNC. The best mechanical properties were obtained with a weight ratio MMT/CNC 1:2, which led to a significant improvement in tensile strength (+ 230%) and tensile modulus (+ 448%). In addition, the thermal stability of the films was also improved, while the water vapor and oxygen transmission rates were reduced. The improved barrier properties were attributed to the nacre-like layered structure formed by the sodium cloisite platelets within the chitosan matrix, which slowed down the diffusion of water and oxygen. Graphical abstract