title: Bioinspired fabrication of hierarchically structured, pH-tunable photonic crystals with unique transition.
abstract: We herein report a new class of photonic crystals with hierarchical structures, which are of color tunability over pH. The materials were fabricated through the deposition of polymethylacrylic acid (PMAA) onto a Morpho butterfly wing template by using a surface bonding and polymerization route. The amine groups of chitosan in Morpho butterfly wings provide reaction sites for the MAA monomer, resulting in hydrogen bonding between the template and MAA. Subsequent polymerization results in PMAA layers coating homogenously on the hierarchical photonic structures of the biotemplate. The pH-induced color change was detected by reflectance spectra as well as optical observation. A distinct U transition with pH was observed, demonstrating PMAA content-dependent properties. The appearance of the unique U transition results from electrostatic interaction between the -NH3(+) of chitosan and the -COO(-) groups of PMAA formed, leading to a special blue-shifted point at the pH value of the U transition, and the ionization of the two functional groups in the alkali and acid environment separately, resulting in a red shift. This work sets up a strategy for the design and fabrication of tunable photonic crystals with hierarchical structures, which provides a route for combining functional polymers with biotemplates for wide potential use in many fields.
authors.affiliation: State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China.
authors.forename: Qingqing
authors.initials: Q
authors.lastname: Yang
authors.forename: Shenmin
authors.initials: S
authors.lastname: Zhu
authors.forename: Wenhong
authors.initials: W
authors.lastname: Peng
authors.forename: Chao
authors.initials: C
authors.lastname: Yin
authors.forename: Wanlin
authors.initials: W
authors.lastname: Wang
authors.forename: Jiajun
authors.initials: J
authors.lastname: Gu
authors.forename: Wang
authors.initials: W
authors.lastname: Zhang
authors.forename: Jun
authors.initials: J
authors.lastname: Ma
authors.forename: Tao
authors.initials: T
authors.lastname: Deng
authors.forename: Chuanliang
authors.initials: C
authors.lastname: Feng
authors.forename: Di
authors.initials: D
authors.lastname: Zhang
mesh_terms: D000818:Animals; D032701:Biomimetics / Q000379:methods*; D002080:Butterflies / Q000033:anatomy & histology; D006863:Hydrogen-Ion Concentration; D049329:Nanostructures / Q000737:chemistry*; D036103:Nanotechnology / Q000379:methods*; D055620:Optical Phenomena; D017785:Photons; D058105:Polymerization; D011109:Polymethacrylic Acids / Q000737:chemistry; D013499:Surface Properties; D014921:Wings, Animal
chemical_list: D011109:Polymethacrylic Acids; C030613:polymethacrylic acid