Multilayered thin films assembled with �green� food contact approved materials (i.e., chitosan (CH), polyacrylic acid (PAA) and montmorillonite (MMT) clay).  Thin coatings of CH/MMT bilayers and CH/PAA/CH/MMT quadlayers were deposited on polylactic acid (PLA) films.  PLA has poor oxygen barrier properties relative to petroleum-based polymers that are widely used as food packaging (e.g. polyethylene terephthalate (PET)). Only ten CH/PAA/CH/MMT quadlayers (~90 nm thick), can cause PLA film to behave like PET in terms of oxygen barrier.  A thirty bilayer CH-MMT assembly (~100 nm thick) on PLA exhibits an oxygen transmission rate (OTR) below the detection limit of commercial instrumentation (=0.005 cm3/(m2�day�atm)). This high barrier behavior is believed to be due to the brick wall nanostructure that produces an extremely tortuous path for oxygen molecules to take as they permeate through the film. The combination of all generally recognized as safe (GRAS) materials, high oxygen barrier and transparency exhibited by this film makes it an ideal candidate for food and other types of high performance packaging.

Clay-chitosan nanobrick walls: Renewable thin films with exceptional gas barrier

244th National Meeting (2012)

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