Highly monodisperse vinyl functionalized silica spheres and their self-assembled three-dimensional colloidal photonic crystals

Current status and future developments in preparation and application of colloidal crystals

“…15,[224][225][226][227] Functional groups such as -NH 2 , -COOH, -OH, -SH, -SO 3 H, -Br, and -CHQCH 2 can be introduced via emulsion copolymerization for polymeric colloids and silane coupling reaction or thiol monolayer assembly for inorganic colloids. [228][229][230][231][232] The introduced functional groups can not only change the surface charge, stability, hydrophobicity and biocompatibility of the formed colloidal crystals, but also provide useful sites for the formation of core-shell composite structures. [233][234][235][236][237] For example, Xia et al demonstrated that polystyrene beads terminated in amine groups could be directly coated with uniform shells of amorphous silica using a modified Stober method, and the band gaps of the formed colloidal crystals could be conveniently changed by controlling the thickness of silica shells.…”

A strategy for fabrication of uniform double-shell hollow microspheres as effective acoustic echo imaging contrast agents through a new polymer-backbone-transition method

“…Synthesis of vinyl-containing organosilica microspheres (VOMs) VTES (3.0 mL) was added to H 2 O (50 mL) under vigorous mechanical stirring (300 rpm) for 2 h. When the organic droplets were completely dissolved and solution was transparent, diluted ammonia solution (1.0 mL, a volume ratio of ammonia : water ¼ 1 : 4) was consecutively added to the reaction mixture via a microsyringe with different dripping speeds and the reaction was allowed to proceed at room temperature for 1 h. The synthesized product was centrifuged, and washed with distilled water and ethanol several times. 39 Synthesis of hollow polymer microspheres (HPMs) VOMs (0.1 g) and an initiator (0.15 mmol) were dispersed in a solvent (water, initiator KPS or ethanol, initiator AIBN) and purged with nitrogen for 30 min. Then, the mixture was heated to 80 C with mechanical stirring at 300 rpm for 6 h. Finally, the obtained microspheres were collected by centrifugation and then dispersed in HF (40 mL, 2.0 wt%) for 3 h to etch the cores.…”

Functional Micro–Nano Structure with Variable Colour: Applications for Anti-Counterfeiting

“…Spraying, atomizing, spin coating, dispensing e self-assembly of biomimetic isotropic films are achieved with a characteristic length-scale comparable to the wavelength of visible light [120] Self-assembled photonic crystals by magnetic field force Magnetic particles and nanospheres (silica [121], polystyrene [122], carbon [123], polyvinylpyrrolidone [124], polyacrylamide [125]) Monodisperse microspheres self-assemble into ordered structures under the action of a magnetic field e self-assembly process is reversible, and the band gap position can also be adjusted by controlling the strength of the magnetic field Self-assembled photonic crystals by gravity Monodisperse microspheres with higher density such as silica [126] Colloidal particles are free to settle and self-assemble into an ordered structure in constant temperature, humidity and vapor pressure environment [127] e photonic crystal obtained by the gravity is difficult to control and is prone to defects [131] Electron beam etching PMMA (positive rubber) and SU-8 (negative rubber) materials [132] Polymer in the region exposed to the electron beam will undergo a soluble change, and the micro-nano structure can be obtained by the developer ere is no need to contact the surface of the material, the deformation is small under stress, and the pollution is less, and the surface of the material is not [86] or ultraviolet irradiation [84,85] e resolution is not affected by the most exposed wavelength, and is closely related to the original template resolution. It has high fidelity, high resolution, low cost and high yield Surface wrinkle technology PDMS [134], polystyrene [135] and shape memory materials [136][137][138][139] are used as base materials, organic polymer materials [140], metal materials [141], and inorganic materials [142] can be used as surface hard layer materials Surface instability factors are induced by heat, force, electromagnetic field, humidity, phase separation, osmotic pressure, capillary force and polymerization…”