A fundamental characteristic of soft matter is the large non-linear response to external forces. The suspension of mono-dispersed particles is considered as representative of a soft matter system. Thermal motion and entropy dominate the motion and transformation of soft matter materials due to the weak interactions of the structural units (in the range of kT). In science, matter is divided into basic soft and hard materials. These attractive forces could make the directional movement of mono-dispersed particles, leading to the formation of a two-dimensional or three-dimensional ordered structure of colloidal crystal (CC) materials. Traditionally, the action of gravity, centrifugal force, pressure, surface tension, electric force, or magnetic force create conditions (concentration, temperature, fluidity, uniformity, and stability over time), under which the forces of attraction prevail over the repulsive forces on average. CCs are three-dimensional ordered periodic structures fabricated by minor particles dispersed uniformly in a solution. pointed out that self-assembly of colloidal clusters with anisotropic building blocks have extended the library of available nanoscale ordered multicompound structures. Self-assembly technique of colloidal crystals (CCs) is considered to be the most promising approach for the preparation of large-area PCs. Research on PCs has been published twice by Science magazine as the world’s major advance in science. Yablonovitch and John have proposed a kind of material with a periodic dielectric structure-photonic crystals (PCs) -whose enormous influence is comparable to that of semiconductor technology. We acquired a profound understanding of the principle and process of self-assembly, which is significant for preparation and application of CCs such as optical filters. Consequently, high-quality CCs were obtained by adjusting temperatures (ordered structure formed at 90 ☌ and solidified at 0 ☌) based on the surface phase rule of the system. The FWHM and reflectivity of CCs showed an increasing trend with increasing temperature. Secondly, a hard sphere system consisting of SPs, PEGDA, and ethanol was established, and the entropy-driven phase transition mechanism of a polydisperse system was expounded. The CCs had been successfully fabricated on the planar interface and presented unfavorable results on the bending interface. Firstly, we clarified the influences of the planar interface and the bending interface on the self-assembly. The influences of refractivity difference, volume fractions, and particle dimension on FWHM were illuminated. The high-quality CCs with high reflectivity (more than 90%) and 9.2 nm narrow FWHM have been successfully fabricated using a fixed proportion of a soft matter system composed of silica particles (SPs), polyethylene glycol diacrylate (PEGDA), and ethanol. Cracks and defects, which could result in lower reflectivity and larger full width at half maximum (FWHM), are the major obstacles for obtaining highly ordered structures of colloidal crystals (CCs).
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