Controllable wettability and adhesion of superhydrophobic self-assembled surfaces based on a novel azobenzene derivative

Abstract

Superhydrophobic surfaces with controllable adhesion have received considerable attention due to their potential in numerous applications. Here, we report a controllable adhesion of superhydrophobic surfaces through tuning the self-assembly structure based on a novel Y-shaped molecule AOB-Y8, consisting of azobenzene groups, 1,3,4-oxadiazole moieties, and three octyl chains. The surface hydrophobicity of AOB-Y8 films was successfully regulated by tuning the assembly morphologies through changing the composition of CHCl₃/CH₃CN mixed solvents, concentration and temperature. Morphological studies of the film prepared from 50 : 50 CHCl₃/CH₃CN solvents revealed that the self-assembled hierarchical, flower-like structure constructs a lot of grooves to trap the surrounding air, generating the superhydrophobic effect at room temperature. Particularly, the surface adhesion of this superhydrophobic film was further regulated from a low level to a very high level by simply changing the concentration of AOB-Y8 in mixed solvents. Meanwhile, the AOB-Y8 self-assembled surfaces showed an excellent chemical resistance to acid and alkali, which is suitable for applications in many environmental conditions. As examples, the tunable adhesive superhydrophobic AOB-Y8 surfaces demonstrated good features to be used in selective transportation of droplets, self-cleaning and droplet-based microreactors to quantitatively detect NaOH and FeCl₃.