Diverse nanotextured surface fabricated by directional photofluidization lithography and their application for wettability control

Nanotextured surface have attracted a great interest due to its application to a promising tool for advanced photonics and interface sciences. Although many impressive results to fabricate such nanotextured surface have been achieved over the last decade, all established methods are still restricted by a number of factors such as limited control of structural features, inherently induced-structural defects, complicated process, and technical barriers caused by mechanical contact. Herein, to overcome those limitations, we suggest a facile and scalable fabrication of nanotextured surface reliefs with precisely controlled structural feature by using directional photofluidization lithography (DPL). In particular, we show that the structural features of nanotextured surface including shapes and modulation heights could be deterministically tunable by adjusting the polarization and irradiation time of interference pattern when irradiated on the pristine azopolymer's line arrays. Moreover, we address a long-lasting question, what is the origin of surface relief gratings (SRGs) formation onto azopolymer film in terms of polymeric bulk photo-flows, directional photofluidization, by a direct visualization of polymeric flow according to the light polarization. Finally, in a practical application of the obtained nanotextured surface, we demonstrate their wetting properties depending on the modulating heights.