Preparation and characterization of multilayer films composed of chitosan, sodium alginate and carboxymethyl chitosan-ZnO nanoparticles.

To deal with serious environmental pollution resulting from plastic packaging materials, biodegradable films using chitosan (CS) are gaining considerable increase gradually. However, chitosan films lack important properties to meet the preserved demands. This study aimed to develop new bio-based films incorporated with carboxymethyl chitosan-ZnO (CMCS-ZnO) nanoparticles and sodium alginate (SA) to overcome the weakness of CS films. CMCS-ZnO nanoparticles were successfully synthesized in the matrix of CMCS through direct precipitation method, which showed an average diameter of 100 nm. Multilayer films with CS film as the outer layer and SA film as the inner layer were prepared by solution casting method. The addition of CMCS-ZnO nanoparticles led to enhanced tensile strength, and to better water vapor resistance. The as-prepared films exhibited distinctive antibacterial activity against S. aureus and E. coli. The results suggested that the as-prepared film is expected to be a promising material for food packaging.