Layer-by-layer (LbL) assembly is wide-reaching conformal coating “platform” technology capable of imparting a multiplicity of functionalities on nearly any type of surface in a relatively environmentally friendly way. At its core, LbL is a solution deposition technique in which layers of cationic and anionic materials (e.g. clay nanoplatelets, polymers and even biological molecules) are built up via electrostatic attractions in an alternating fashion. Here we are producing nanocomposite multilayers having 10 – 96 wt% clay that are completely transparent and exhibit oxygen transmission rates below 0.005 cm<sup>3</sup>/m<sup>2</sup>●day (at a film thickness below 100 nm). This exceptional oxygen barrier makes these layers interesting for food and flexible electronics packaging. Contrary to popular belief, these films can be deposited very quickly (seconds per layer) and maintain near perfect clay platelet orientation. I’ll also describe how these films can also act as a barrier to hydrogen gas, reducing the permeability of a 51 mm polystyrene film 1000X with only a 122 nm thick coating containing five clay layers. All of the materials described are water-based and processing occurs under ambient conditions in most cases.

Clay nanobrick wall multilayer thin films: Processing and gas permeability and separation

251st National Meeting (2016)

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