Angle- and strain-independent coloured free-standing films incorporating non-spherical colloidal photonic crystals

Yeo, Seon Ju; Tu, Fuquan; Kim, Seung Hyun; Yi, Gi‐Ra; Yoo, Pil J.; Lee, Daeyeon

doi:10.1039/c4sm02482f

Cited by 43 publications

(45 citation statements)

References 38 publications

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“…Such assemblies are typically created via evaporation of a solvent from a droplet containing colloids. These droplets can be created via microfluidics 105,203 or ink-jet printing. 204,205 For more information, a recent review covers many of the aspects of these types of photonic crystals.…”

Section: Factors Affecting Optical Applicationsmentioning

confidence: 99%

A colloidoscope of colloid-based porous materials and their uses

et al. 2016

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Nature evolved a variety of hierarchical structures that produce sophisticated functions. Inspired by these natural materials, colloidal self-assembly provides a convenient way to produce structures from simple building blocks with a variety of complex functions beyond those found in nature. In particular, colloid-based porous materials (CBPM) can be made from a wide variety of materials. The internal structure of CBPM also has several key attributes, namely porosity on a sub-micrometer length scale, interconnectivity of these pores, and a controllable degree of order. The combination of structure and composition allow CBPM to attain properties important for modern applications such as photonic inks, colorimetric sensors, self-cleaning surfaces, water purification systems, or batteries. This review summarizes recent developments in the field of CBPM, including principles for their design, fabrication, and applications, with a particular focus on structural features and materials' properties that enable these applications. We begin with a short introduction to the wide variety of patterns that can be generated by colloidal self-assembly and templating processes. We then discuss different applications of such structures, focusing on optics, wetting, sensing, catalysis, and electrodes. Different fields of applications require different properties, yet the modularity of the assembly process of CBPM provides a high degree of tunability and tailorability in composition and structure. We examine the significance of properties such as structure, composition, and degree of order on the materials' functions and use, as well as trends in and future directions for the development of CBPM.

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Section: Factors Affecting Optical Applicationsmentioning

confidence: 99%

A colloidoscope of colloid-based porous materials and their uses

et al. 2016

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“…When colloidal particles are regularly arranged with submicrometer sizes, their interaction with light results in a strong wavelength‐selective reflection, called the structural color. The structural color does not tend to fade away over time; thus, many researchers have tried to apply the structural coloration to create a new type of pigment with an antifading property . In addition, the structural color can be responsive to variations in physical conditions, such as temperature, pressure, and humidity; therefore, the application of these materials to various types of sensors has been proposed …”

Section: Introductionmentioning

confidence: 99%

Grating Diffraction or Bragg Diffraction? Coloration Mechanisms of the Photonic Ball

Ohnuki

Isoda

Sakai

et al. 2019

Advanced Optical Materials

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bandgap frequency. Recently, the macroscopic shape of the photonic crystal has been considered as another factor that can produce additional optical effects. [13][14][15] One example is the spherical aggregation of colloidal particles, which is called the photonic ball. [16][17][18][19][20] The spherical symmetry makes the wavelength of reflection independent of the angle when observed under the backscattering geometry. Recently, Vogel et al. reported a detailed optical investigation of the photonic ball from a hierarchical structure viewpoint. [20] The photonic ball usually consists of the primary colloidal particles that are several hundred nanometers in diameter, while the size of the spherical aggregation can be up to several hundred micrometers. Figure 1a shows an example of the photonic ball consisting of 250 nm diameter silica particles, where the strong green reflection is present near the center of the ball. This reflection is explained by Bragg diffraction, which is caused by the stacking of the (111) planes in the face-centered cubic (FCC) lattice. The wavelength of reflection exhibits a red shift when the primary particles become large, as would be expected from the Bragg condition. However, the photonic ball appears very differently when the primary particles increase in diameter to, for example, 400 nm. As shown in Figure 1b, an iridescent reflection appears in the peripheral region, while the central part looks weakly blue. The mechanism causing this iridescent reflection is controversial. Kim et al. considered Bragg diffraction from various planes in the crystal similar to the reflection observed in the central region. [17] In contrast, Vogel et al. recently suggested that the reflection is caused by the diffraction from the surface grating consisting of periodically arranged colloidal particles. [20] The iridescent reflection is observed to be a ring-shaped one, although the ring is not uniformly bright with dark regions (Figure 1b). The reflection appears at a specific angular position between the surface normal and the optical axis of the microscope (i.e., the direction of the epi-illumination). This result seems consistent with the diffraction theory because the angle of incidence directly relates to the wavelength of reflection. However, when the photonic ball is macroscopically observed with the naked eyes, it appears green as shown in Figure 1c. This feature is supported by spectroscopic measurements. The reflectance spectra have a peak at 515 nm corresponding to the green color (see the Supporting Information). This wavelength selectivity seems difficult to explain through a simple diffraction theory.The coloration mechanism of the photonic ball is investigated, which is a spherical aggregation of submicrometer-sized colloidal particles. An interesting optical property is reported for photonic balls with colloidal particles larger than 400 nm: a ring-like iridescent reflection appears on the peripheral part of the ball when observed under an optical microscope. Previous studies considered ...

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“…Such films containing buckled or spherical supraparticles show angle and strain independent reflections due to the colloidal matrices provided by the supraparticles. This leads to observable structural coloring [116]. Such films can be obtained from emulsion droplets using osmotic annealing and defined salt-concentration to produce buckled or spherical supraparticles and entrapping them in a silicon matrix.…”

Section: Applications Of Supraparticlesmentioning

confidence: 99%

Droplets, Evaporation and a Superhydrophobic Surface: Simple Tools for Guiding Colloidal Particles into Complex Materials

Sperling

Gradzielski

2017

Gels

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Abstract:The formation of complexly structured and shaped supraparticles can be achieved by evaporation-induced self-assembly (EISA) starting from colloidal dispersions deposited on a solid surface; often a superhydrophobic one. This versatile and interesting approach allows for generating rather complex particles with corresponding functionality in a simple and scalable fashion. The versatility is based on the aspect that basically one can employ an endless number of combinations of components in the colloidal starting solution. In addition, the structure and properties of the prepared supraparticles may be modified by appropriately controlling the evaporation process, e.g., by external parameters. In this review, we focus on controlling the shape and internal structure of such supraparticles, as well as imparted functionalities, which for instance could be catalytic, optical or electronic properties. The catalytic properties can also result in self-propelling (supra-)particles. Quite a number of experimental investigations have been performed in this field, which are compared in this review and systematically explained.

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Angle- and strain-independent coloured free-standing films incorporating non-spherical colloidal photonic crystals

Cited by 43 publications

References 38 publications

A colloidoscope of colloid-based porous materials and their uses

A colloidoscope of colloid-based porous materials and their uses

Grating Diffraction or Bragg Diffraction? Coloration Mechanisms of the Photonic Ball

Droplets, Evaporation and a Superhydrophobic Surface: Simple Tools for Guiding Colloidal Particles into Complex Materials

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