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

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. [GRAPHICS] .