Fast and Reproducible Wettability Switching on Functionalized PVDF/PMMA Surface Controlled by External Electric Field

In this paper, the novel material with controllable wettability switching triggered by external electric field is developed. The material is based on the piezopolymer blend of poly(methyl methacrylate) (PMMA) and polyvinylidene difluoride (PVDF), grafted with various hydrophobic and hydrophilic molecules to alter the initial wettability of polymer films. Organic functional groups are grafted on the blend surface via formation of covalent bonds between PMMA and arenediazonium tosylates. The surface chemical structure and morphology of prepared samples are studied by X-ray photoelectron spectroscopy, UV-vis, and attenuated total reflection infra red (ATR-IR) spectroscopies, atomic force microscopy (AFM), and confocal microscopy. Attachment of gold nanoparticles to grafted thiol chemical groups is additionally used to confirm the modification procedure. Application of external stimuli in the form of the electric field leads to dramatic changes in water contact angle. Wettability switching is found to be extremely fast and completely repeatable without the destructions of the polymer film. Mechanism of switching is attributed to the morphological smoothening of piezoelectric responsible composite PVDF-PMMA under the application of external stimuli.