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Chitosan (C) and zein (Z) were used to develop bilayer films with a characteristic one-way water barrier using a layer-by-layer (LBL) casting method. The effects of mass ratios (C:Z 1:1 , C:Z 1:2 , C:Z 1:3 , C:Z 3:1 , C:Z 2:1) on the microstructure and physicochemical properties of bilayer films were investigated. Bilayer films had uniform microstructures, and C:Z = 1:3 showed a firmer structure as the Z aggregates were distributed in the continuous phase of C. The intermolecular interactions between the C and Z layers were observed using FTIR and XRD analysis. TGA demonstrated that adding Z layer enhanced the thermal stability of C films. LBL coating gave the C/Z bilayer film an increased elongation and tensile strength, as well as a decreased water vapor and oxygen permeability, especially for C:Z = 1:3 which had better properties. The results suggested that C and Z bilayer films may be a promising material for food packaging with the desired water resistance. [Display omitted] • A bilayer film based on chitosan and zein was fabricated by LBL casting method. • Physicochemical property can be tuned by the zein layer. • The bilayer films showed excellent water resistance and mechanical properties. • The C:Z 1:3 films had better mechanical and barrier properties. [ABSTRACT FROM AUTHOR]

To overcome the limitations of chitosan (CS) and konjac glucomannan (KGM), the bilayer films of CS and KGM were prepared by layer-by-layer (LBL) casting method, and the effects of different mass ratios (i.e., C5: K0, C4:K1, C3:K2, C1:K1, C2:K3, C1:K4, and C0:K5) on the microstructures and physicochemical properties of bilayer films were examined to evaluate their applicability in food packaging. The results revealed that the bilayer films had uniform microstructures. When compared with pure films, the bilayer films displayed lower swelling degrees and water vapor permeability. However, the tensile tests revealed a reduction in the mechanical properties of the bilayer films, which was nonetheless superior to that of the pure KGM film. In addition, the intermolecular interactions between the CS and KGM layers were observed through FTIR and XRD analyses. Finally, TGA and DSC analyses demonstrated a decrease in the thermal stability of the bilayer films. Our cumulative results verified that CS-KGM bilayer films may be a promising material for use in food packaging and further properties of the bilayer films can be supplemented in the future through layer-by-layer modification and the addition of active ingredients. • There was good material compatibility between CS and KGM, which formed a uniform and dense bilayer structure. • Compared with pure films, the bilayer films displayed lower swelling degrees and water vapor permeability. • Complexed with CS significantly improves the mechanical properties and reduces the water solubility of pure KGM film. • The optimum mass ratio of CS and KGM in the bilayer films is suggested to be 1:1. [ABSTRACT FROM AUTHOR]