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Fabrication of Artificial Melanin-Based Structural Color Materials through Biomimetic Design
Published in Akihiro Miyauchi, Masatsugu Shimomura, Biomimetics, 2023
When dopamine is polymerized in a mixed water/methanol solvent, black polydopamine particles with relatively uniform particle sizes can be obtained [10]. By concentrating the obtained aqueous dispersion of submicron-sized polydopamine particles and constructing an assembled structure, a structural color corresponding to the particle diameter was observed (Fig. 12.2) [10]. Since polydopamine particles disperse well in water, structural coloration by spray painting was also possible. Following the structural coloration mechanism in nature, by creating an assembled structure with black particles of uniform size, light scattering was suppressed, and vivid structural coloration was realized by polydopamine particles. These colors are structural colors resulting from scattering that occurs due to the assembly of submicron-sized polydopamine particles. The dispersion properties of the particles can also be controlled by coating the surface of the polydopamine particles with a magnetic surfactant [11] or modifying the surface by constructing graft polymers by living polymerization [12].
Conclusions and Perspectives
Published in Yi Long, Yanfeng Gao, Vanadium Dioxide-Based Thermochromic Smart Windows, 2021
Yi Long, Yanfeng Gao, Xuchuan Jiang
VO2 film coatings with an unattractive yellow or brown color, or even a dark-blue color, on glass is another big barrier to the commercialization due to the strong absorption of such coatings. Different cultures may require certain modifications to tune the color. Although some simulations have suggested that doping may be an effective strategy to alter the color by shifting the adsorption edges, experimental results have shown that only limited changes can be achieved. Complexion with dyes or responsive matrixes, either organic or inorganic, can modulate the original color of VO2 at the expense of the thermochromic properties of VO2 films or transparency, which may not be a good solution in some applications. Structural coloration as discussed in Chapter 6 has proved effective in altering the color, but some degradation of the thermochromic performance and the complicated fabrication approach need to be investigated further. To address this concern, more creative ideas are needed.
Nanostructural coloration
Published in Ching Eng Png, Yuriy Akimov, Nanophotonics and Plasmonics, 2017
Structural coloration with metallic and other high-index dielectric nanostructureshas several advantages:Wide variation in resulting colors by slight tweaking of geometrical parameters.Long-term chemical stability and reduced susceptibility to radiation enables col-ors to retain their quality for a long duration in contrast to dyes and other pigments.Extremely compact size gives an advantage in comparison to thin film, multilayeror photonic crystal based structural coloration.Ability to juxtapose spectral filtering elements with pixel sizes far smaller than thecurrent state-of-the-art allows very high resolution image sensors and full colorprinting/display, and other related applications.
Progress in polydopamine-based melanin mimetic materials for structural color generation
Published in Science and Technology of Advanced Materials, 2020
Our group has conducted research on colorless functionalized PDA thin films [56–58] and morphology control of PDA thin films [59]. In the course of these studies, it was found that by polymerizing dopamine in a water/methanol mixed solvent, monodisperse PDA particles can be obtained. In 2015, our group reported that a bright structural color was observed from the assembled structure obtained by concentrating an aqueous dispersion of monodisperse PDA particles that mimic melanin granules (Figure 4(a,b)) [60]. These colors were scattering-derived structural colors that result from the assembly of submicron-sized PDA particles, and the color tone was controlled by simply selecting the size of particles used. In addition, the color tone could be changed by attaching hairy polymer chains to the surface of PDA particles. When PDA particles grafted with a hydrophilic hair polymer were assembled, the tone of the structural color was controlled by the change in interparticle distance [61]. Since PDA particles were well dispersed in water [62], structural coloration by spray painting was also possible (Figure 4(c)) [60]. By coating PDA particles, which were well dispersed in an aqueous solvent, with a magnetic surfactant, the dispersibility in organic solvents was improved, and the color was changed by a magnetic field [63]. The coloring mechanism in nature was reproduced, and bright structural coloration that suppressed light scattering was realized by constructing a microstructure with PDA particles of uniform size.
Magnetic and optical properties of porous anodic alumina/co composite films with gradual microstructures
Published in Journal of Modern Optics, 2019
Shu Min Yang, Yun Kai Qi, Li Jun Zheng, Jian Jun Gu
Structural colouration is an optical effect caused by the periodical microstructure of an organism and has numerous advantages as a physical colour. Some of these merits include never fading and high reflectivity and polarization properties (1). International research groups (2,3) have applied a wide range of methods to imitate the structural colour of organisms, such as holography lithography (4), technique of self-assembly (5), and ink-jet printing (6). Diggle et al. (7) reported that a thin PAA film oxidized in oxalic acid produces a bright colour in the visible light range, although the saturation was very low. Liu et al. (8) applied an impulse current to induce the cyclic oxidation of Al foil and found that by adjusting the periodical density of current, the structural colour of thin film can be improved. Wang et al. (9) effectively increased the saturation of colour by depositing non-metal nanowires in PAA composite thin films, but yet this required a complex preparation process. Xu et al. (10,11) found that the colour saturation of the PAA thin film was enhanced saliently by removing the Al substrate on the backside, but the films became more fragile after the removal. Recently, Zhang et al. (12-14) deposited Co, Fe, and Ni nanowires in PAA nanopores to control the magnetic and optical properties of PAA film, and acquired a PAA composite thin film of a certain mechanical strength and high saturated single structural colour.
A BRDF study on the visual appearance properties of titanium in the heating process
Published in Journal of Modern Optics, 2018
Yanlei Liu, Kun Yu, Longfei Li, Yuejin Zhao, Zilong Liu, Yufang Liu
The measurement of BRDF for the samples shows that: (1) the incident zenith has a postive influence on the BRDF of all the samples; (2) the BRDF curve vs. wavelength is independent to the incident and view direction; (3) the heated samples show obviously light absorption, and the position of strong absorption moves to long wavelength with the increase of heating time. As mentioned above, the structural colouration is associated with the scattering, interference and diffraction of light. It is well known that the colour generated by interference and diffraction varies with the change of view direction. As presented in our results, for given wavelength, periodical change of light intensity does not occurs with the variation of view direction. The results of measurement conform to the characteristics of pigment colouration rather than the structural colouration. We may conclude that the colours of Ti are pigment colouration and may be generated by intermediate products during heating process.