title: Photonic Crystals with a Reversibly Inducible and Erasable Defect State Using External Stimuli.
abstract: The controlled introduction of artificial extrinsic defects is critical to achieve the functions of photonic crystals. Smart defects capable of responding to external stimuli lead to more advanced applications. Here we report a microgel colloidal crystal with a defect state which could be induced and erased reversibly by external stimuli. The crystal was assembled from PNIPAM microgel and P(NIPAM-AAc) microgel of the same size. The resulting doped crystal does not exhibit a defect state in its stop band because of the similar optical properties of the dopant and the host. By increasing the pH value, however, the dopant P(NIPAM-AAc) spheres swell to a larger size and turn into real defects in the crystal, resulting in the appearance of defect state. Adjusting the pH value back restores the size of the dopant spheres, and thus erases the defect state. Temperature, a second external stimulus, could also be used to induce and erase defect states of the crystal.
authors.affiliation: Key Laboratory of Functional Polymer Materials and State Key Laboratory of Medicinal Chemical Biology, The Co-Innovation Center of Chemistry and Chemical Engineering of Tianjin, Institute of Polymer Chemistry, College of Chemistry, Nankai University, Tianjin 300071 (China).
authors.forename: Mao
authors.initials: M
authors.lastname: Chen
authors.affiliation: Key Laboratory of Functional Polymer Materials and State Key Laboratory of Medicinal Chemical Biology, The Co-Innovation Center of Chemistry and Chemical Engineering of Tianjin, Institute of Polymer Chemistry, College of Chemistry, Nankai University, Tianjin 300071 (China).
authors.forename: Yapeng
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Functional Polymer Materials and State Key Laboratory of Medicinal Chemical Biology, The Co-Innovation Center of Chemistry and Chemical Engineering of Tianjin, Institute of Polymer Chemistry, College of Chemistry, Nankai University, Tianjin 300071 (China).
authors.forename: Siyu
authors.initials: S
authors.lastname: Jia
authors.affiliation: Key Laboratory of Functional Polymer Materials and State Key Laboratory of Medicinal Chemical Biology, The Co-Innovation Center of Chemistry and Chemical Engineering of Tianjin, Institute of Polymer Chemistry, College of Chemistry, Nankai University, Tianjin 300071 (China).
authors.forename: Lin
authors.initials: L
authors.lastname: Zhou
authors.affiliation: Key Laboratory of Functional Polymer Materials and State Key Laboratory of Medicinal Chemical Biology, The Co-Innovation Center of Chemistry and Chemical Engineering of Tianjin, Institute of Polymer Chemistry, College of Chemistry, Nankai University, Tianjin 300071 (China).
authors.forename: Ying
authors.initials: Y
authors.lastname: Guan
authors.affiliation: Key Laboratory of Functional Polymer Materials and State Key Laboratory of Medicinal Chemical Biology, The Co-Innovation Center of Chemistry and Chemical Engineering of Tianjin, Institute of Polymer Chemistry, College of Chemistry, Nankai University, Tianjin 300071 (China). yongjunzhang@nankai.edu.cn.
authors.forename: Yongjun
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D000178:Acrylamides / Q000737:chemistry; D000180:Acrylic Resins / Q000737:chemistry; D003102:Colloids / Q000737:chemistry; D003460:Crystallization; D005782:Gels / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D010316:Particle Size; D017785:Photons; D013696:Temperature
chemical_list: D000178:Acrylamides; D000180:Acrylic Resins; D003102:Colloids; D005782:Gels; C052970:poly-N-isopropylacrylamide
keywords: artificial defects; colloidal crystals; defect states; microgels; stimuli-responsive materials