Dual-responsive wettability of poly o-toluidine nanofiber coating fabricated by interfacial polymerization

To date, smart surfaces with controllable wettability have received extraordinary attention due to their great importance in both fundamental research and practical applications. Chemical composition and surface topography are the two key factors to affect the wettability of solid surfaces. Applying external stimuli to change the surface chemistry and/or topography is considered to be a valuable approach for driving the transition between hydrophilicity and hydrophobicity of surfaces. In this study, poly o-toluidine nanofibers were synthesized by a facile aqueous/organic interfacial polymerization, and superhydrophobic coatings of poly o-toluidine were prepared via a room-temperature spraying process. The reversible wettability conversion between the superhydrophobic and the hydrophilic state of the obtained poly o-toluidine coating under ultraviolet irradiation and electric stimulation was investigated. From the X-ray photoelectron spectroscopy analysis, this intelligent switching wetting behavior under ultraviolet light irradiation was confirmed to have a high correlation with the change in surface chemical composition. When the electric stimulation was applied, the wettability switch was caused by the redistribution of charge and electric dipole along the liquid–solid interface.