Epoxy−Clay Fabric Film Composites with Unprecedented Oxygen-Barrier Properties

• Published in: Chemistry of materials Vol. 18; no. 18; pp. 4393 - 4398
• Main Authors: Triantafyllidis, Kostas S, LeBaron, Peter C, Park, In, Pinnavaia, Thomas J
• Format: Journal Article
• Language: English
• Published: American Chemical Society 05.09.2006
• ISSN: 0897-4756; 1520-5002
• DOI: 10.1021/cm060825t

A new barrier-film chemistry is described in which two materials, namely a clay fabric film and a polymer, are combined to form a composite with gas-barrier properties that are far superior to those of the parent end members. Homoionic inorganic smectite clay fabric films of sodium montmorillonite and synthetic lithium fluorohectorite were cast in self-supported film form, impregnated with liquid epoxy resin and amine curing agent, and then cured to form the final epoxy−clay fabric film composite. The oxygen permeabilities of the epoxy−clay fabric film composites were lower by 2−3 orders of magnitude in comparison to that of the pristine polymer and by 3−4 orders of magnitude in comparison to that of the pristine clay film. This unprecedented reduction in oxygen permeability was attributed in part to the high volume fraction (∼77%) of highly aligned and nonswellable clay nanolayers in the fabric film and to the polymer filling of voids formed between imperfectly tiled clay platelet edges in the film. Mixed organic−inorganic ion-exchange forms of clay fabric films made through ion-exchange reactions of inorganic clay films form a heterostructure in which the outer regions of the film contain a swellable organoclay phase and the interior regions retain the nonswellable inorganic clay barrier phase. The modulus and glass-transition temperature of the polymer phase is not compromised upon formation of the clay fabric film composites.