Wettability of monolayer graphene/single-walled carbon nanotube hybrid films

The wettability of monolayer graphene has been reported to be transparent. In this work, we study the wettability of monolayer graphene using single-walled carbon nanotube (SWNT) films as the substrate. Compared to the water contact angles of 86.3 degrees for monolayer graphene and 131.6 degrees for SWNTs, the water contact angle of the graphene/SWNT hybrid films is found to be 106.5 degrees. This suggests that the wettability of monolayer graphene is not transparent, but somewhat half-transparent. The mechanisms of these results are suggested and discussed. Considering the atomic thickness of graphene materials, the modification of the wettability of surfaces by applying graphene materials on the underlying substrates provides wide potential applications for wettability control.