Improving Mechanical and Water Stability of Graphene Oxide and Polymer Composite Films for Protective Barrier Applications

Graphene Oxide (GO) nanosheet films are of interest as barriers to prevent exposure to toxic liquids and vapors. However, pure GO films are not mechanically stable and not stable to water immersion and need to be toughened while retaining their barrier properties. This project focuses on designing GO/polymer film composites and GO-embedded polymer sandwich structured films. A set of water-soluble polymer binders and cross-linking agents were screened, both individually and with GO for mechanical and water stability. These polymer binders included synthetic polymers, elastomeric coatings, and liquid rubber. The composite film screening criteria included the durability and strength of the films, through tensile, bend, and water immersion stability tests. Films showing promise were further tested for vapor permeability. Nacre films containing cross linked methylcellulose or polyallylamine with glutaraldehyde were found to have significantly increased mechanical and water stability compared to unmodified GO films, passing all three screening tests. Six sandwich-structure films also passed all three screening tests. To affirm these modified films still operated as barriers, water vapor transmission and permeability, as well as hexane permeability, of the promising films were tested. With these successes, robust GO and polymer film composites affirm the potential for GO nano sheets to operate as highly effective protective barriers, which could operate as barriers to UV light, antibacterial coatings, and protection from chemical and environmental toxins. Further testing is also in process to investigate both the stretchability and breathability of these films.