title: Influence of clay concentration on the gas barrier of clay-polymer nanobrick wall thin film assemblies.
abstract: The influence of the clay deposition suspension concentration on gas barrier thin films of sodium montmorillonite (MMT) clay and branched polyethylenimine (PEI), created via layer-by-layer assembly, was investigated. Films grown with MMT suspension concentrations ranging from 0.05 to 2.0 wt % were analyzed for their growth as a function of deposited polymer-clay bilayers (BL) and their thickness, clay concentration, transparency, nanostructure, and oxygen barrier as a function of the suspension concentration. The film thickness doubles and the visible light transmission decreases less than 5% as a function of MMT concentration for 20-BL films. Atomic force and transmission electron microscope images reveal a highly aligned nanobrick wall structure, with quartz crystal microbalance measurements revealing a slight increase in the film clay concentration as the MMT suspension concentration increases. The oxygen transmission rate (OTR) through these 20-BL composites, deposited on a 179 μm poly(ethylene terephthalate) film, decreases exponentially as a function of the MMT clay concentration. A 24-BL film created with 2.0 wt % MMT has an OTR below the detection limit of commercial instrumentation (<0.005 cc/m(2)·day·atm). This study demonstrates an optimal clay suspension concentration to use when creating LbL barrier films, which minimizes deposition steps and the overall processing time.
authors.affiliation: Materials Science & Engineering Program, Texas A&M University, College Station, Texas 77843, USA.
authors.forename: Morgan A
authors.initials: MA
authors.lastname: Priolo
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Holder
authors.forename: Daniel
authors.initials: D
authors.lastname: Gamboa
authors.forename: Jaime C
authors.initials: JC
authors.lastname: Grunlan
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry*; D001546:Bentonite / Q000737:chemistry*; D000077215:Clay; D008567:Membranes, Artificial; D010316:Particle Size; D011094:Polyethyleneimine / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D000538:Aluminum Silicates; D008567:Membranes, Artificial; D001546:Bentonite; D011094:Polyethyleneimine; D000077215:Clay