Convenient and Efficient Fabrication of Colloidal Crystals Based on Solidification-Induced Colloidal Assembly.

Laixi Sun,Chun Yang,Xuan Luo,Shufan Chen,Ting Shao,Xin Ye

doi:10.3390/nano9040575

Laixi Sun, Chun Yang + Show 4 more

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https://doi.org/10.3390/nano9040575

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Abstract

The simple yet efficient and versatile fabrication of colloidal crystals was investigated based on the solidification-induced colloidal crystallization process with particle/water suspension as precursor. The resulting colloidal crystals were constituted by crystal grains with sizes ranging from several tens of micrometers to a few millimeters. Each of the grains had a close-hexagonal array of colloids, which endowed the bulk colloidal crystal powders with some specific optical properties. The freezing of water was shown as the major driving force to form colloidal crystal grains, which supersaturated the solution with nanoparticles and thus induced the formation and growth of colloidal crystal seeds. This process is intrinsically different from those conventional methods based on shearing force, surface tension, columbic interaction or magnetic interaction, revealing a new strategy to fabricate colloidal crystals in a convenient and efficient way.

Highlights

Photonic crystals (PCs) are periodic structures with a refractive index variation on the scale of the light wavelength
Among the wide variety of PC forms, the ordered assembly of colloidal nanoparticles, which is known as colloidal crystals, is one of the most promising PC materials [5,6,7]
Various methods have been investigated for the preparation of colloidal crystals, which are mostly based on the self-assembly of colloidal nanoparticles

Summary

Introduction

Photonic crystals (PCs) are periodic structures with a refractive index variation on the scale of the light wavelength. Strong capillary force at the meniscus induces the ordered assembly of spheres into thin planar opals depositing on the substrate This method is quite time-consuming where several days are often necessary especially when multilayered colloidal crystals are prepared. Electrostatics can be used to assist the spontaneous assembling process for increasing the fabrication speed [35] Another powerful technique is the melt-shear organization, which involves the compression of hard core–soft shell particles between the plates with heating [36,37,38]. It is restricted to hard core–polymer shell particles Besides these traditional methods, external electric fields or magnetic fields are introduced in some cases to induce the self-assembly of charged colloidal particles or magnetic particles [39,40]. The investigation of new method to fabricate colloidal crystals in a simple, high-throughput and flexible way is still desired

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Conclusion