Multiresponsive PEDOT–Ionic Liquid Materials for the Design of Surfaces with Switchable Wettability

Among the different types of stimuli‐responsive polymers, conjugated polymers reveal unique multiresponsive behavior. In this work, the synthesis and characterization of new functional poly(3,4‐ethylenedioxythiophenes) (PEDOT) bearing imidazolium ionic‐liquid moieties (PEDOT‐Im) is reported. PEDOT‐Im polymers show multiresponsive properties to a variety of stimuli, such as temperature, pH, oxidative doping, and presence of anions. These stimuli provoke different changes in PEDOT‐Im, such as changes in color, oxidation state, and, wetting behavior. In all cases, a reversible effect is observed, and the polymers reveal responsive properties in solution as well as in the form of thin films. Whereas sensitiveness to pH and oxidative doping are known phenomena for other PEDOT derivatives, responsiveness to temperature and to anions is a unique property of PEDOT‐Im. The anion exchange is further investigated by means of the Quartz Crystal Microbalance with dissipation. Anion exchanges induce fast, adjustable, and reversible contact angle changes between 24° and 107°. As a potential application, surfaces with switchable wettability triggered by anion solutions are prepared by spin‐coating PEDOT‐Im films onto different substrates.