Polyolefin films with outstanding barrier properties based on one-step coassembled nanocoatings

Polyolefin (PO) films are commonly used for food packaging and other consumer applications. However, while polyolefins are good water vapor barriers, they are highly permeable to oxygen. To resolve this issue, montmorillonite (MMT) nanosheets were one-step coassembled with polyvinyl alcohol (PVA) chains via facile and scalable dip coating. In a one-step coassembly process, MMT nanosheets are aligned to form a nacre-like structure with PVA chains by gravity-induced shear as the aqueous coating dispersion flows and subsequently dries on the substrate surface. The surface properties of the PO substrates were modified using high-power corona discharge treatment. The resulting nanocoating layer had vastly improved barrier properties, especially against oxygen, thanks to the highly ordered nacre-like structure of the assembled MMT nanosheets creating a tortuous path for gas transport. The structure of the nanocoatings was verified via X-ray diffraction (XRD) and small angle X-ray scattering (SAXS). This nanocoating technique has unique implications for thin film vapor barrier technology such as food packaging materials, biomedical devices, and construction materials.Graphical abstractExfoliated montmorillonite (MMT) nanosheets were coassembled with polyvinyl alcohol (PVA) binder in a one-step dip-coating system.