The hollow ball has a cavity structure inside, and the thickness of the shell layer is at the nanometer level or the micro-nano level. Compared with other bulk materials, hollow ball with a shell thickness ranging from nanometers to micrometers , has the advantages of high specific surface area and low density, and the shell of this hollow sphere material can be adjusted accordingly as needed, obtain special performance. Due to this special structure, compared with other materials of the same particle size, it has high specific surface area, low density, surface permeability, thermal insulation and light scattering energy performance.
Preparation of Hollow Ball Material by Soft Template Method
(1) Emulsion droplets are used as templates to prepare hollow sphere materials
The basic process of preparing hollow sphere materials using emulsion droplets is: adding a reactant precursor to a system consisting of water, surfactant and its oil phase, and the precursor obtains the target product through a chemical reaction at the water-oil interface. The key to preparing hollow sphere materials from emulsion droplets is to obtain stable droplets. It is very important to select suitable surfactants and solvents, and the solvents cannot be mutually dissolved. At present, this method has been used to successfully synthesize hollow spherical materials such as Cu2O, SiO2, CuS, and TiO2.
(2) Preparation of hollow ball material by micellar method
Due to the special amphiphilic nature of ionic surfactants, when its concentration exceeds the critical micelle concentration (CMC), it will spontaneously aggregate to form micelles, which can provide templates for the preparation of hollow sphere materials, block copolymers It is composed of different component blocks together. The difference in solubility of the block components can promote self-assembly to form a core-shell micelle, which can provide a template for the synthesis of hollow sphere materials.
(3) Preparation of hollow sphere materials using vesicles as templates
At present, there are more and more reports about the preparation of hollow sphere materials from vesicles formed by surfactants as templates. There are two main synthesis routes: one reactant directly reacts in the vesicle bilayer membrane. The shell layer is formed; the other is to deposit metal ions on the outer wall of the vesicle through chemical reactions such as sol-gel method or precipitation method.
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