Biomimetic Submicroarrayed Cross-Linked Liquid Crystal Polymer Films with Different Wettability via Colloidal Lithography

Photoresponsive cross-linked liquid crystal polymer (CLCP) films with different surface topographies, submicropillar arrays, and submicrocone arrays were fabricated through colloidal lithography technique by modulating different types of etching masks. The prepared submicropillar arrays were uniform with an average pillar diameter of 250 nm and the cone bottom diameter of the submicrocone arrays was about 400 nm, which are much smaller than previously reported CLCP micropillars. More interestingly, these two species of films with the same chemical structure represented completely different wetting behavior of water adhesion and mimicked rose petal and lotus leaf, respectively. Both the submicropillar arrayed film and the submicrocone arrayed film exhibited superhyrophobicity with a water contact angle (CA) value of 144.0 ± 1.7° and 156.4 ± 1.2°, respectively. Meanwhile, the former demonstrated a very high sliding angle (SA) greater than 90°, and thus, the water droplet was pinned on the surface as rose petal. On the contrary, the SA of the submicrocone arrayed CLCP film consisting of micro- and nanostructure was only 3.1 ± 2.0°, which is as low as that of lotus leaf. Furthermore, the change on the wettability of the films was also investigated under alternating irradiation of visible light with two different wavelengths, blue light and green light.