Nanoplatelet-loaded thin film for gas and water vapor barrier: clay and graphene

Oppositely-charged polymer–clay layer-by-layer (LbL) thin films show good gas barrier properties due to a nanobrick wall structure consisting of clay nanoplatelets within the polymeric mortar. It is shown here that additional polymer layer reduces the free volume of the film by filling in gaps of the similarly charged clay layer and increases the oxygen barrier performance by at least one order of magnitude. Highly aligned platelets with some non-continuous clay stacks were imaged within the microtomed LbL thin film by TEM. For water vapor barrier, graphene is used to prevent clay swelling by the water. Graphene-filled polymer bulk demonstrated enhanced barrier as well as mechanical properties at an optimal graphene concentration. The super gas barrier, transparent nanocoatings obtained are useful for a variety of food, pressurized, and flexible electronics packaging applications. (author)