High Moisture Barrier with Synergistic Combination of SiOx and Polyelectrolyte Nanolayers

The lifespan of most organic electronics, and many types of food, depend on the oxygen and moisture barrier of the packaging materials. Despite exhibiting excellent oxygen barrier and being relatively easy to produce, polyelectrolyte multilayer nanocoatings (PEM) show limited moisture barrier. SiOx thin films can exhibit good moisture barrier, but rigidity that leads to cracking is a challenge for flexible packaging. In this work, layer‐by‐layer assembled PEM coatings are paired with inorganic SiOx to form a three‐layer sandwich‐type moisture barrier. The barrier property of this organic/inorganic/organic structure is an order of magnitude better than any individual component or other combination thereof. This behavior is attributed to the underlying PEM layer smoothing the substrate surface and the top PEM layer eliminating defects in the underlying SiOx. This study provides a new twist in the development of flexible films with exceptional moisture barrier.