Conductive oxygen barrier films using supramolecular assembly of graphene embedded polyelectrolyte multilayers
By Gokhale, Ankush A.; Lu, Jue; Parker, Nathan J.; Izbicki, Andrew P.; Sanyal, Oishi & Lee, Ilsoon
Published in Journal of Colloid and Interface Science
2013
Abstract
The supramolecular self-assembly of polyelectrolyte multilayers (PEMs) provides robust bottom-up strategies to assemble a broad spectrum of nanostructures on the host substrates. In this study, we discuss the formation of graphene nanoplatelet (GNP) embedded polyelectrolyte films to enhance the oxygen barrier properties of poly(ethylene terephthalate) (PET) films. Despite cheaper costs and high mechanical strength, the diffusion of small gas molecules such as oxygen through PET films remains a matter of great concern. The simple yet robust supramolecular deposition of GNP/polyelectrolyte on PET substrates significantly increases the tortuous path the oxygen molecule has to travel, making it harder to diffuse through the PET film. With permeability coefficients in the range of 10 -18 cc cm/cm2 s Pa, the coatings developed in this study show three orders of magnitude reduction as compared to the permeability coefficient of the bare PET film, significantly lower than that of ethylene vinyl alcohol (EVOH) and comparable to silicon oxide thin films used in commercial gas barrier foils. The use of GNPs in the multilayered films also helped reduce the electrical sheet resistance to about 1 MΩ which is five orders of magnitude lower than the original PET substrate opening up promising opportunities for future use in semiconductor and electronics industry. Making suitable modifications in the deposition process, three configurations of GNP embedded PEM multilayers namely hydrogen bonded, electrostatic, and composite films were developed and their effect on oxygen barrier property and sheet resistance was monitored. Oxygen permeability of films was tested in accordance with ASTM D-3985 using a MOCON 2/21 ML instrument, whereas electrical sheet resistance was quantified using a Gamry Femtostat Electrochemical Impedance station.