262646 Ultrathin and Transparent Nanobrick Wall Super Gas Barrier Assemblies
Ultrathin and transparent nanobrick wall super gas barrier assemblies*
Thin films of natural, sodium montmorillonite clay and weak polyelectrolytes were prepared by alternately dipping a PET substrate into four different dilute aqueous mixtures (polyethylenimine, poly(acrylic acid), polyethylenimine, and montmorillonite clay). After depositing four of these quadlayers (QL), the resulting transparent film exhibits an oxygen transmission rate at or below the detection limit of commercial instrumentation (≤ 0.005 cm3 m-2 day-1). This level of oxygen barrier, which is unprecedented for a clay-filled polymer composite, is believed to be due to a nanobrick wall microstructure comprised of completely exfoliated clay bricks in polymeric mortar and clay layer spacing on the order of tens of nanometers. This 4 QL film, with a thickness of only 51 nm and optical transparency of 95%, represents a true foil replacement technology, useful for flexible electronic displays, microwaveable food containers, and pharmaceutical packaging.
* Submitted to AIChE 08A12.
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