Recent work with multilayer nanocoatings composed of poly-electrolytes and clay has demonstrated the ability to prepare super gas barrier layers from water that rival inorganic CVD-basedfilms (e.g., SiOx). In an effort to reduce the number of layers required to achieve a very low oxygen transmission rate (OTR (<0.01 cc/m2 day atm)) in these nanocoatings, buffered cationicchitosan (CH) and vermiculite clay (VMT) were deposited using layer-by-layer (LbL) assembly. Buffering the chitosan solution and its rinse with 50 mM Trizmabase increased the thickness of these films by an order of magnitude. The OTR of a 1.6-μm-thick, six-bilayer film was 0.009 cc/m2 day atm, making this the best gas barrier reported for such a small number of layers. This simple modification to the LbL process could likely be applied more universally to produce films with the desired properties much more quickly.
Guin, Tyler, Michelle Krecker, David Austin Hagen, Jaime C. Grunlan