Fabrication of patterned and anti-patterned azopolymer nanoarrays via the light-induced nanowetting method

The template wetting method is a common method used for preparing one-dimensional polymer nanostructures, which can be widely applied in many fields. Although the template wetting method has generality in controlling the morphology of nanomaterials, it still poses challenges in generating patterned polymer nanoarrays. Here, we present the fabrication of patterned and anti-patterned azopolymer (PAzo) nanoarrays via the light-induced nanowetting method. By shining UV lights, the trans-PAzo converts to cis-PAzo, causing a reduction of the glass transition temperature (T_g) of the PAzo below room temperature. Consequently, the PAzo polymers can undergo reversible solid–liquid transitions by shining UV and visible lights. When PAzo films are covered with photomasks and anodic aluminum oxide (AAO) templates, followed by shining UV lights, patterned PAzo nanoarrays can be generated. We further apply the concept that cis-PAzo films can be selectively removed by solvents to generate anti-patterned PAzo nanoarrays. By covering PAzo films with photomasks and illuminating UV lights, the unmasked areas can be converted to cis-form, which can then be selectively removed by selected solvents. The patterned PAzo films are then covered with AAO templates, followed by shining UV lights, forming hierarchical anti-patterned PAzo nanoarrays.