Long-lifetime, superhydrophobic, free-standing carbon infiltrated vertically aligned carbon nanotube structures

Abstract

Long lifetime, free-standing, superhydrophobic, carbon infiltrated vertically aligned carbon nanotube structures (ct-VACNT) are prepared by VLS-assisted VACNT growth on photolithographic patterned catalyst wafers, followed by a carbon infiltration process creating c-VACNT precursor structures (made from a nanoporous carbon sponge material) which are subsequently released from the catalyst wafers, surface roughened on their top and bottom surface and then conformally overcoated with a few nm thick hydrophobic thin film of a hydrophobic amorphous fluoropolymer, thus resulting in free-standing superhydrophobic ct-VACNT structures. Longevity testing of the hydrophobic overcoating shows that the addition of a customized surface roughening step (especially in the form of low-pressure O2 plasma-assisted surface burning of the nanocarbon sponge material) for the bottom and top surfaces is key to extending the hydrophobic lifetime of such ct-VACNT structures from a few weeks to over a year.These long-lifetime ct-VACNT structures can now be used to develop novel fluid processing devices for a range of industrial and medical fluid processing applications requiring gas transfer into and/or out of aqueous liquids. Such novel fluid reactor devices are enabled by application-specific optimized components made from these novel nano-to macro ct-VACNT structures, in the form of Fluid channel Array Bricks (FABs).