Oleophobic coated composite materials based on multi-layer graphitic scaffolding: applications within aircraft propellant tanks and oil-spill clean-up

The preparation of oleophobic materials coated with a composite based on a multi-layer graphitic scaffolding is reported herein. A range of substrates were employed for this purpose including Kevlar, carbon fibre, glass fibre, nylon and stainless steel mesh. These were utilised, in comparison with free-standing film versions of the composite material, to investigate their enhanced ability to facilitate water penetration whilst simultaneously retaining the oleophobic behaviour. The materials demonstrated efficient oil/water separations and reusability. The free-standing films and coated substrates were characterised in detail via a range of spectroscopic and analytical techniques. Contact angle measurements for aviation Jet A-1 fuel on various coated substrates ranged from 96.9-107.0 degrees whilst for hexadecane and silicone oil, contact angles of 90.6-120.3 degrees and 74.5-103.3 degrees were recorded, respectively. These values were slightly lower than the contact angles for the corresponding free standing film versions which were 111.9 degrees, 126.4 degrees and 105.9 degrees for Jet A-1 fuel, hexadecane and silicone oil, respectively. BET surface area analysis of composite and films showed type IIb isotherms with H3-type hysteresis. T-Plot analysis was carried out to quantify external surface area of the composite and film in comparison to the base multilayered graphitic material scaffold. The morphology of the materials was analysed by SEM imaging to show the extent and degree of coating on the composite material upon the substrates. The application of these coated substrates as membranes within the context of aircraft propellant tanks and oil-spill removal was also explored, suggesting that coated carbon fibre and coated nylon serve as promising candidates for oil/water separation within these applications.