A variety of functional thin films can be produced using the layer-by-layer
assembly technique. In this work, assemblies of anionic clay and cationic polymer were
studied with regard to film growth and gas barrier properties. A simple, yet flexible
robotic dipping system, for the preparation of these thin films, was built. The robot
alternately dips a substrate into aqueous mixtures with rinsing and drying in between.
Thin films of sodium montmorillonite clay and cationic polymer were grown and studied
on poly(ethylene terephthalate) film or a silicon wafer. After 30 clay polymer bilayers
were deposited, the resulting transparent film had an oxygen transmission rate (OTR)
below 0.005 cm3/m2/day/atm. This low OTR, which is unprecedented for a clay-filled
polymer composite, is believed to be due to a ?brick wall? nanostructure comprised of
completely exfoliated clay bricks in polymeric ?mortar?. The growth of polymer and clay
assemblies is then shown to be controlled by altering the pH of polyethylenimine (PEI).
Growth, oxygen permeability, and mechanical behavior of clay-PEI assemblies were
studied as a function of pH in an effort to tailor the behavior of these thin films. Thicker
deposition at high pH resulted in reduced oxygen permeability and lower modulus, which
highlights the tailorability of this system.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-2008-12-116 |
| Date | 14 January 2010 |
| Creators | Jang, Woo-Sik |
| Contributors | Grunlan, Jaime C. |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation |
| Format | application/pdf |
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