Title: Phototunable Morpho Butterfly Microstructures Modified by Liquid Crystal Polymers

Author: Xin Qing, Yuyun Liu, Jia Wei, Ran Zheng, Chongyu Zhu, Yanlei Yu*

Journal: Adv. Optical Mater., 2019, 7(3), 1801494.

Abstract:

The unique hierarchical microstructures of the Morpho butterfly wing (MBW) exhibit angle independent blue iridescence. Biomimicking these microstructures and turning them into functional photonic crystals (PhCs) have fascinated scientists yet remain challenging. Here, a phototunable PhC is fabricated by depositing the azobenzene‐containing linear liquid crystal polymer (LLCP) onto the MBW template. Thanks to the excellent mechanical properties and deformability of LLCP, the generated 3D bilayer microstructures demonstrate hierarchical deformation upon UV light irradiation, leading to a blueshift of the reflection peak (70 nm) and a remarkable change of reflectance (40%). This phototunable PhC may have potential applications in pigments, cosmetics, and sensors.

Fulltext Link: https://onlinelibrary.wiley.com/doi/full/10.1002/adom.201801494

This paper demonstrates a new approach to fabricate phototunable PhCs with hierarchical microstructures by coating azo-LLCP onto the natural MBW. The LLCP was deposited onto the MBW surface through electrospinning, which turned the LLCP solution into dry microscale fibers without altering the microstructures. A further melting and annealing process produced a well-orientated LLCP coating onto MBW to achieve a photoresponsive LLCP-MBW composite. The hierarchical microstructures of MBW including scales, ridges, and even lamella spacing will deform upon low-energy UV light irradiation. The detailed structure–reflection relationship is analyzed in this work to demonstrate that the deformation of hierarchical microstructures of LLCP-MBW could be adjusted by the light intensity, resulting in a large blueshift of the reflection peak and a tunable reflection intensity. Moreover, the change of reflectance could be restored by visible light, which is expected to be applied in the field of light sensors.