Self-assembling, bioinspired wax crystalline surfaces with time-dependent wettability

One of the most fascinating properties of materials in nature is the superhydrophobic and self-cleaning capabilities of different plant surfaces. This is usually achieved by the hydrophobic cuticles that are made of cutin and contain wax crystals both within them and on their surfaces. Here, bioinspired n-hexatriacontane wax films are deposited via thermal evaporation and it is shown that the surface evolves in time via self-assembly. This leads to a dramatic change in the wetting properties with a transition from hydrophobic to superhydrophobic characteristics, which takes place within several days at room temperature. This phenomenon is investigated and strain-induced recrystallization is proposed to be the mechanism for it. This work could become the basis for the inspiration and production of tuned, time-dependant, temperature-sensitive, variable-wettability surfaces. Bioinspired wax films exhibit time-dependent nanostructure evolution that includes strain release and a nanoroughness increase. Nanoroughness evolution leads to time-dependent wettability changes, from hydrophobic to superhydrophobic. The mechanism for the nano-roughness increase is most likely recrystallization induced by residual strain that develops during the rapid film formation. This provides a basis for the production of tuned, time-dependent, temperature-sensitive material surfaces with changeable wettability.