Reversible photo-controllable surface wettability of epoxy-polyurethane smart coating

HERRERA JÉSICA MICAELA; PENOFF MARCELA ELISABETH; GALANTE MARÍA JOSÉ

PROGRESS IN ORGANIC COATINGS

ELSEVIER SCIENCE SA

Lugar: Amsterdam; Año: 2023 vol. 179 p. 107509 - 107509

0300-9440

Light-responsive materials, in which a rapid and reversible response can be achieved, are of particular interest for several technological applications. The transformation of external stimuli into mechanical energy is very promising in the field of molecular motors and energy convertors. Azobenzenechromophores undergo photon-driven reversible cis-trans isomerization. In these stimuli responsive materials, reversible molecular motion, especially the molecular mechanical movement on a surface, can be responsible for the switching of surface properties, like surface wettability. In this work the authors synthesized a fluorinated epoxy - isocyanate thermosetting coating (EPUF) modified with an azobenzene derivative (AZO). The increase of the AZO content in the surface by migration during synthesis, as a consequence of the presence of fluorine, leads to changes in the surface hydrophobicity, when UV light is used as stimulus. First, polyurethane precursors (PUs) based on isophoronediisocyanate (IPDI), a fluorinated diol and AZO were synthesized. SEC, FTIR and UV-visible spectroscopy techniques were used to characterize the precursors. The subsequent polyurethane – epoxy reaction allowed preparing azo modified epoxy networks. The resulting materials were characterized using different techniques. Fluorinated and pristine networks were compared. The changes in contact angle, roughness and mechanical behavior by UV irradiation were analyzed. The reversible photo-induced switching of the surface properties of the fluorine-AZO modified coatings makes them potentially useful for multiple technological applications, in which cycling surface properties will result of a great utility.