Facile Synthesis of Monodispersed SiO₂@Fe₃O₄ Core–Shell Colloids for Printing and Three-Dimensional Coating with Noniridescent Structural Colors

Abstract

Amorphous photonic structures (APSs) with short-range ordered arrangement have attracted great interest because of their wide view angles. However, the presented methods for the APSs color printing and 3D coating on different substrates and curvatures are lack of control. Here, APSs with angle-independent structural colors were fabricated by the self-assembly of SiO 2 @Fe 3 O 4 core–shell nanostructures, which were prepared by the hydrolysis of Fe(acac) 3 on the silica surfaces. The size of SiO 2 @Fe 3 O 4 core–shell colloids can be controlled well through the tuning of SiO 2 particle size, whereas the coverage of Fe 3 O 4 on silica surfaces can be precisely tailored through altering the mass ratio between Fe 3 O 4 precursor and SiO 2 . APSs with only short-range ordered structures, uniform noniridescent structural colors, and high color visibility can be obtained through the self-assembly of SiO 2 @Fe 3 O 4 colloids of different particle sizes in a few minutes. They are mainly attributed to the weak electrostatic repulsion interactions between SiO 2 @Fe 3 O 4 colloids because of the partial coverage of Fe 3 O 4 on silica surfaces and absorption of the incoherent multiple scattering of visible light from Fe 3 O 4 . Moreover, SiO 2 @Fe 3 O 4 colloids show good adhesion to various substrates, such as paper, glass, plastics, resins, ceramics, and wood, which facilitates the formation of uniform APSs on different substrates. Multicolor prints and 3D coating of APSs on substrates with different curves and roughness can be realized on the basis of the fast assembly of SiO 2 @Fe 3 O 4 colloids.

Highly Efficient Fabricating Amorphous Photonic Crystals Using Less Polar Solvents and the Wettability‐Based Information Storage and Recognition

“…The structural color and the stop band of photonic crystals can be controlled through altering the lattice constant, refractive index, or the orientations of ordered structures. These unique properties enable PCs to show considerable applications in color display, [ 1–8 ] sensing, [ 9–22 ] printing, [ 23–29 ] anticounterfeiting, [ 30–38 ] photocatalysis, [ 39–41 ] optical device, [ 42–46 ] and solar energy. [ 47–50 ]…”

Thermally stable high-contrast iridescent structural colours from silica colloidal crystals doped with monodisperse spherical black carbon particles

“…A similar enhancement of structural colours by adding a black-coloured component was reported in systems based on artificial colloidal crystals as well as in nature. [15][16][17][18][19][20][21][22][23][24][25][26][27][28] Most of those studies employed black-coloured coating [22][23][24][25][26][27][28] or used a black material as the background. 13 A previous study suggested that the black materials improve the saturation of structural colours by absorbing scattered light in a broad wavelength range.…”

“…Some researchers tried to enhance the contrast of structural colours by adding black-coloured materials. [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] For instance, adding a small amount of carbon black powder to a colloidal crystal of polystyrene nanoparticles reduced the incoherent scattering considerably. [16][17][18][19][20][21][22] A black coating on the nanoparticles could also increase the saturation of structural colours.…”

“…[16][17][18][19][20][21][22] A black coating on the nanoparticles could also increase the saturation of structural colours. [23][24][25][26][27][28] As a result, effective improvements have been made in various structural colours (from blue to red) based on the size, refractive index, and packing structure of nanoparticles. However, in both strategies mentioned above, the introduction of black-coloured materials was also detrimental to the iridescent colour effect by disturbing the particle arrangement in the colloidal crystal.…”

Simple and Ultrafast Fabrication of Invisible Photonic Prints with Reconfigurable Patterns

“…By introducing responsive building blocks, polymers, or other components into the colloidal photonic crystals, responsive photonic crystals can be prepared and their color can be changed depending on the physical or chemical stimulations . These photonic crystals with brilliant structural colors have attracted considerable interests due to their growing applications in the field of reflection mode‐based color display, sensor, printing, anti‐counterfeiting, optical device, photocatalysis, and solar cell …”