Programmable surface anisotropy from polarization-driven azopolymer reconfiguration

Abstract

The ability to accurately realize complex textures is of great relevance for tailoring surface-driven functionalities as wettability, adhesion and light diffraction. The fabrication of superficial micro-textures, in a simple and cost-effective way, is high desiderable in this framework. A versatile technique for surface micropatterning is based on reconfiguration of photosensitive azobenzene-containing polymers, in which a macroscopic light-induced motion of polymer chains, fueled by the photo-isomerizing azobenzene molecules, allows the controlled optical reshaping of prestructured superficial micro-textures. Here, azopolymer surfaces, prepatterned with an array of discrete cylindrical micropillars, are reconfigured through a polarization-driven large-scale surface deformation until achieving superficial gratings with programmable amplitude, orientation and periodicity. The high degree of structural surface anisotropy, the possibility to program the directionality of such anisotropy from the reconfiguration of basic pristine surfaces, and the simplicity of the optical setup, make the proposed structuration method attractive for versatile and cost-effective surface patterning.