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

Abstract

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.

Rapid, Template‐Less Patterning of Polymeric Interfaces for Controlled Wettability via in Situ Heterogeneous Photopolymerizations

“…Even when extrapolating the phase separation behavior to the most extreme heterogeneity possible: the formation of an amphiphilic interface with pure PVDF and pure HDDA:OCTA network domains, the slight hydrophilicity of PVDF limits the extent of water repellency attainable from these networks. As prior demonstrations of amphiphilic interfaces with domains of varying compositions show, selective presentation of hydrophobic moieties on elevated, rough features can impart bulk hydrophobic character to the surface. Here, since the fluoropolymer is actually just slightly hydrophilic its selective presentation at the interface cannot explain the associated dramatic increase in contact angle.…”

“…In one study, spatial organization of compositionally different domains has been demonstrated via the use of membranes or masks to selectively direct surface functionalization with more hydrophilic/hydrophobic moieties than the base substrate material . The need for a mask or membrane is eliminated if a heterogeneous blend is employed as a base substrate, allowing for spatially resolved secondary functionalization of hydrophobic/hydrophilic moieties based on the characteristics of the blend morphology . These approaches can lead to interfaces with a wide range of wetting behaviors and depending on the materials employed, surfaces with switchable wettability have also been demonstrated .…”

“…[23] The need for a mask or membrane is eliminated if a heterogeneous blend is employed as a base substrate, allowing for spatially resolved secondary functionalization of hydrophobic/hydrophilic moieties based on the characteristics of the blend morphology. [24] These approaches can lead to interfaces with a wide range of wetting behaviors and depending on the materials employed, surfaces with switchable wettability have also been demonstrated. [22][23][24] A drawback with these approaches is that again a lengthy fabrication procedure that entails substrate development and at least two secondary functionalization steps are needed to achieve surface topography and spatially resolved chemical gradients.…”

“…[24] These approaches can lead to interfaces with a wide range of wetting behaviors and depending on the materials employed, surfaces with switchable wettability have also been demonstrated. [22][23][24] A drawback with these approaches is that again a lengthy fabrication procedure that entails substrate development and at least two secondary functionalization steps are needed to achieve surface topography and spatially resolved chemical gradients.…”

Multiresponsive Wettability Switching on Polymer Surface: Effect of Surface Chemistry and/or Morphology Tuning

“…Recently, dual‐responsive or multiresponsive intelligent surfaces have engendered wide favor as their structure and properties can be reversibly regulated with several stimuli . Most actual reports deal with systems responding to the combined effect of temperature and pH . Materials sensitive to alternative or additional stimuli such as light irradiation, ions, or biomolecules have also been explored .…”