Innovative Poly(vinyl alcohol) (PVA)-Based Nanolayered Films: Balancing Mechanical and Gas Barrier Properties.

Poly(vinyl alcohol) (PVA), while offering exceptional gas barrier performance, faces significant challenges due to its extensive hydrogen bonding network. This structure limits its mechanical flexibility and creates processing difficulties, particularly during thermal melt processing, as the temperature window between melting and decomposition is narrow. To address these limitations, this study explores the multifunctional properties of nanostructured multilayer films composed of PVA and ethylene vinyl alcohol copolymer (EVOH). By engineering nanometric layers within the multilayer structure, we preserved the outstanding oxygen and water vapor barrier capabilities of the materials while enhancing the flexibility of the films. The findings reveal that reducing individual layer thicknesses to the nanoscale improves EVOH macromolecular mobility, leading to notable changes in thermal behavior. The formation of more regular crystalline structures and the complex interplay at the interfaces between PVA and EVOH layers significantly impedes the diffusion of small molecules across the film. Furthermore, mechanical testing demonstrates that increasing the number of layers enhances the ductility of the films, an effect attributed to the expanded interfacial area and a lower degree of crystallinity. These advancements highlight the potential for optimizing multilayer film structures to balance the barrier and mechanical performance.