Chitosan-based films exhibit good oxygen barrier that degrades when exposed to high humidity. In an effort to overcome this drawback, a multilayer nanocoating consisting of crosslinkable chitosan (CHQ) and poly(acrylic acid) [PAA] was deposited on polyethylene terephthalate (PET) using layer-by-layer (LbL) assembly. Chitosan (CH) was functionalized with glycidyl methacrylate to introduce acrylic functionalities within the film. The deposited films were crosslinked using a free radical initiator and crosslinking is confirmed with FTIR and reduced film thickness. A 10 bilayer (BL) crosslinked CHQ/PAA film, that is only 165 nm thick, results in a 36X reduction of the oxygen transmission rate (OTR) of 175 mm thick PET at 90% relative humidity (RH). To achieve these same results without crosslinking, a 15 BL CH/PAA film, that is almost 5X thicker, must be deposited on PET. This environmentally-friendly, transparent nanocoating is promising for food packaging or protection of flexible electronics, especially in high humidity environments.

Crosslinkable, chitosan-enabled, moisture-resistant multilayer gas barrier thin film

2019 Spring National Meeting

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