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    Patterning Hierarchy in Direct and Inverse Opal Crystals
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    Abstract:
    Abstract Biological strategies for bottom‐up synthesis of inorganic crystalline and amorphous materials within topographic templates have recently become an attractive approach for fabricating complex synthetic structures. Inspired by these strategies, herein the synthesis of multi‐layered, hierarchical inverse colloidal crystal films formed directly on topographically patterned substrates via evaporative deposition, or “co‐assembly”, of polymeric spheres with a silicate sol–gel precursor solution and subsequent removal of the colloidal template, is described. The response of this growing composite colloid–silica system to artificially imposed 3D spatial constraints of various geometries is systematically studied, and compared with that of direct colloidal crystal assembly on the same template. Substrates designed with arrays of rectangular, triangular, and hexagonal prisms and cylinders are shown to control crystallographic domain nucleation and orientation of the direct and inverse opals. With this bottom‐up topographical approach, it is demonstrated that the system can be manipulated to either form large patterned single crystals, or crystals with a fine‐tuned extent of disorder, and to nucleate distinct colloidal domains of a defined size, location, and orientation in a wide range of length‐scales. The resulting ordered, quasi‐ordered, and disordered colloidal crystal films show distinct optical properties. Therefore, this method provides a means of controlling bottom‐up synthesis of complex, hierarchical direct and inverse opal structures designed for altering optical properties and increased functionality.
    Keywords:
    Colloidal crystal
    Template
    Crystal (programming language)
    Template
    Colloidal crystal
    Polystyrene
    Crystal (programming language)
    Template method pattern
    Emulsion polymerization
    Morphology
    We present a facile strategy to prepare grape-like silica-based hierarchical porous interlocked microcapsules (HPIMs) by polystyrene colloidal crystals templates, whose structure is the subtle integration of open mouthed structure, hierarchical porous nanostructure and interlocked architecture. HPIMs are fabricated by replicating colloidal crystals templates that have a hexagonal close-packed structure; thus, theoretically, each microcapsule has 12 open mouths, and these open mouths with mesoporous microcapsule wall construct the hierarchical porous structure. Furthermore, the interlocked architecture of the microcapsules can endow HPIMs with excellent mechanical stability and recyclability. By adjusting sulfonation time, the morphology, shell thickness, and even mesporous size of the HPIMs can be precisely controlled. In addition, HPIMs with various compositions are obtained via this method, such as silica and aminopropyl polysilsesquioxane (APSQ). All these unique features derived from a readily available method will give products with a broader range of applications.
    Template
    Colloidal crystal
    Polystyrene
    Template method pattern
    Abstract Summary: A numerical method is presented for simulating charged colloidal dispersions in electrolyte solutions. Utilizing a smoothed profile for colloid‐solvent boundaries, efficient mesoscopic simulations are enabled for modeling dispersions of many colloidal particles exhibiting many‐body electrostatic interactions. The validity of the method was examined for simple colloid geometries, and the efficiency was demonstrated by calculating stable structures of two‐dimensional dispersions, which resulted in the formation of colloidal crystals. Formation of a charged colloidal crystal. magnified image Formation of a charged colloidal crystal.
    Colloidal crystal
    Mesoscopic physics
    Colloidal particle
    Crystal (programming language)
    Citations (17)
    We present a new procedure to prepare high-quality colloidal crystals at a flat wall, which was oriented vertically in a colloidal suspension. The method is based on the depletion-induced effective attraction between the colloidal particles themselves and between the colloidal particles and a flat wall. The concentrations of the colloidal particles and the depletion agents (polymers in this case) were chosen in such a way that phase transition occurred not only at the wall but also in the bulk. In this way, good conditions were obtained to form high-quality colloidal crystals, consisting of several layers, at a flat wall in a relatively short time period. The crystals formed were characterized with atomic force microscopy.
    Colloidal crystal
    Colloidal particle
    Suspension
    Particle (ecology)
    Crystal (programming language)
    Citations (12)
    Well-controlled porous morphologies and tailored shapes are important for the mesostructures that are produced in material chemistry. Hard template processes provide an efficient way to fabricate porous structures, but the only a few particle shapes can be produced using 3D porous templates. Little is discussed about how such templates affect the shapes of particles. Here, porous Cu2O crystals with different shapes and degrees of branching can be electrodeposited using colloidal crystal templates. These templates can produce particle shapes that are exactly the same as those created without templates, but they can also produce different shapes than those fabricated on bare substrates (without a colloidal crystal template). The presence of the colloidal crystal template blocks ion diffusion and changes the deposition environment. Both increased and decreased degrees of branching can be produced when different electrolyte systems are used in conjunction with a colloidal crystal template.
    Template
    Colloidal crystal
    Branching (polymer chemistry)
    Template method pattern
    Particle (ecology)
    Crystal (programming language)
    Colloidal particle
    Citations (11)
    Macroporous metals with strong diffractive properties at visible wavelengths can be synthesized from colloidal crystal templates. The synthesis, characterization, and potential applications of macroporous metals created in this manner are summarized in this article. The Figure shows a macroporous copper film, illustrating the long-range order of the porous structure (see also cover).
    Template
    Colloidal crystal
    Characterization
    Macroporous metals with strong diffractive properties at visible wavelengths can be synthesized from colloidal crystal templates. The synthesis, characterization, and potential applications of macroporous metals created in this manner are summarized in this article. The Figure shows a macroporous copper film, illustrating the long-range order of the porous structure (see also cover).
    Template
    Colloidal crystal
    Characterization
    A series of monodispersed P(St-MMA-AA) colloids with diameters from 200 nm to 500 nm was synthesized successfully using emulsion polymerization. The corresponding colloidal crystals were fabricated and investigated. UV-Vis reflectance spectra showed that the band gaps of the obtained colloidal crystals accord well with Bragg law. The height, phase and spectrum 2D images of the obtained binary colloidal crystals were studied using different modes of atom force microscopy.
    Colloidal crystal
    Emulsion polymerization