Light-Responsive Conductive Surface Coatings on the Basis of Azidomethyl-PEDOT Electropolymer Films

The design of responsive coatings has gained increasing attention recently, with light-responsive interfaces receiving particular appreciation, as their surface properties can be modulated with excellent spatiotemporal control. In this article, we present light-responsive conductive coatings acquired through a copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) reaction between electropolymerized azide-functionalized poly(3,4-ethylenedioxythiophene) (PEDOT-N) and arylazopyrazole (AAP)-bearing alkynes. The UV/vis and X-ray photoelectron spectroscopy (XPS) data indicate a successful post-modification, supporting a covalent attachment of AAP moieties to PEDOT-N. The thickness and degree of PEDOT-N modification are accessible by varying the amount of passed charge during electropolymerization and time of reaction, respectively, providing a degree of synthetic control over the physicochemical material properties. The produced substrates demonstrate a reversible and stable light-driven switching of photochromic properties in both "dry" and swelled states, as well as efficient electrocatalytic Z → E switching. The AAP-modified polymer substrates exhibit a light-controlled wetting behavior, demonstrating a consistently reversible switching of the static water contact angle with a difference up to 10.0° for CF-AAP@PEDOT-N. The results highlight the application of conducting PEDOT-N for the covalent immobilization of molecular switches while preserving their stimuli-responsive features.