Layer-by-layer assembled graphene stacks were deposited on TPU membranes as coatings to enhance permeation properties.
Flexible barrier films that resist to gas permeation have a wide range of applications in various industrial sectors, from food packaging to electronics and aerospace. Especially for the latter, it is important to use lightweight materials that demonstrate sufficient diffusion resistance. Thermoplastic Polyurethane (TPU) films are widely used in this sector, as they combine flexibility, elasticity and chemical resistance. Nevertheless, their inherent permeability to gases is a major drawback that needs improvement.
Reduced gas diffusion properties
In the present work, scientists have prepared stacks of chemical vapor deposited graphene films which were then deposited on TPU films as coatings. Helium leak tests verified the enhanced permeation properties of the multistacked graphene coatings: The graphene /TPU membranes exhibited reduced gas diffusion properties by 9.9 % with respect to bare TPU. By increasing the number of graphene layers to five, the permeation of the graphene coatings was reduced by 25.2 %. The above performance is attributed to the intrinsic nature of the mixed order-stacked graphene layers, which prevents local defects from coincidence, thus decreasing the leakage of the He gas through the film.
The work indicates a novel promising approach towards the preparation of graphene-based gas-barrier coatings, that can be of interest for numerous applications.