Thin, transparent composite films consisting of water-soluble polymer and high aspect ratio clay platelets have been successfully constructed using the layer-by-layer assembly procedure. A substrate was alternately dipped in polyethylenimine (PEI) and vermiculite (VMT) clay platelets to produce a highly organized structure that exhibits extremely low oxygen permeability. Vermiculite clay was chosen for this process due to its high aspect ratio (1 nm thick and 1.1 micron diameter) and impermeability to oxygen and other atmospheric gasses. The films produced were found to consist of more than 96 wt% VMT, were greater than 95% transparent, and exhibited super gas barrier behavior (1.9x10-21 O2 permeability) at thicknesses less than 165 nm.  Combining these properties with their high flexibility and ambient processing conditions, these films are great candidates for many barrier applications, including food and flexible electronics packaging.

Transparency, gas barrier, and moisture resistance of vermiculite nanobrick wall thin films

245th National Meeting (2013)

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