Stretching and Bending of Azopolymer Nanorod Arrays via Laser-Induced Photo-Fluidization

Regular arrays of anisotropic polymer nanomaterials have attracted great attention because of their unique properties and various applications such as solar cell devices, sensors, and supercapacitors. The control of the shape manipulation and tailored properties of individual polymer nanomaterials in arrays, however, remains a great challenging task. In this work, we demonstrate a versatile approach to fabricate elliptical and bent polymer nanorod arrays through laser-induced photo-fluidization of azobenzene-containing polymers (azopolymers). Ordered anodic aluminum oxide (AAO) membranes are used as templates for generating azopolymer nanorod arrays via a solvent vapor annealing-induced wetting method. After being released from the AAO templates and shone by linearly polarized lights, the nanorod arrays can be transformed into anisotropic nanostructures, driven by the trans-to-cis and cis-to-trans isomerization of the azobenzene groups in the azopolymers. Depending on whether the laser beam is shone at normal or tilt angles of incidence, elliptical or bent nanorod arrays can be prepared, respectively. The deformation degrees and water wettabilities of the nanorod arrays can be varied by changing the illumination times. This study reports a beneficial route to prepare ordered arrays of anisotropic polymer nanostructures for advanced applications.