Structural colored gels for tunable soft photonic crystals

Abstract

A periodically ordered interconnecting porous structure can be embodied in chemical gels by using closest-packed colloidal crystals as templates. The interconnecting porosity not only provides a quick response but also endows the porous gels with structural color arising from coherent Bragg optical diffraction. The structural colors revealed by porous gels can be regulated by several techniques, and thus, it is feasible to obtain desirable, smart, soft materials. A well-known thermosensitive monomer, N-isopropylacrylamide (NIPA), and other minor monomers were used to fabricate various structural colored gels. The selection of minor monomers depended on the targeted properties. This review focuses on the synthesis of templates, structural colored porous gels, and the applications of structural colored gel as smart soft materials for tunable photonic crystals.

Self-assembled organic and polymer photonic crystals for laser applications

“…Monodispersed colloidal microparticles with a diameter of several hundred nanometers are known to show the self-assembly from a colloidal suspension into 3D ordered lattice structures (Figure 2b). [81][82][83][84][85][86][87][88][89][90][91] Such 3D ordered structures of microparticles are called 'CCs' . Notably, no special facilities are required for the fabrication of CC structures due to bottom-up process of microparticle assembly.…”

“…According to the equations (6) and (7), the reflection wavelength can be tuned by controlling the refractive indices, particle radii and filling ratio. [81][82][83][84][85][86][87][88][89][90][91] The artificial CC structures have been for the first time experimentally prepared by natural sedimentation of colloidal silica microparticles, leading to the extensive development of CCs into the PC research field. 92 To date, much effort has established prevalent guidelines for fabricating high-quality CC films by vertical deposition of a substrate in a suspension, lifting of a substrate from a suspension, shearing of a suspension between substrates, and so forth.…”

“…92 To date, much effort has established prevalent guidelines for fabricating high-quality CC films by vertical deposition of a substrate in a suspension, lifting of a substrate from a suspension, shearing of a suspension between substrates, and so forth. [81][82][83][84][85][86][87][88][89][90][91] With respect to photonic device applications, the recent CC research advances have been directed toward the development of an extensive variety of optical reflection sensors and displays that are capable of shifting the reflection wavelength, that is PBG wavelength, by changes in external stimuli, such as the temperature, ionic strength, pH, photoirradiation, and electric and magnetic fields. [81][82][83][84][85][86][87][88][89][90][91] However, the previous reports have been made on the fabrication of optical reflection devices by utilizing passively the reflection properties of CC films.…”

Tunable structural color in organisms and photonic materials for design of bioinspired materials

“…From the viewpoint of bottom-up nanotechnology, nanostructured colloidal crystals can be fabricated using a simple and low cost process. A large number of research papers on opal photonic crystals were published in the past decade, as reviewed in references [53][54][55][56][57][58][59][60].…”

“…Inverse opal hydrogels have potential applications in chemical sensors [73,74], and elastomer inverse opal films can be used for mechanical fingerprinting [75]. Tunable structural color in inverse opal photonic crystals was overviewed in [53,56,57].…”