Nanoparticles refer to particles with a particle size between 1-100nm (nanoparticles are also called ultrafine particles). It belongs to the category of colloidal particle size. They are in the transition zone between clusters of atoms and macroscopic objects, between the microscopic system and the macroscopic system. They are groups composed of a small number of atoms or molecules, so they are neither typical microscopic systems nor typical macroscopic systems.
Method of preparing nanoparticles
Ultrasonic self-assembly method–Using the assistance of ultrasound, the interaction between substances forms nanoparticles. It is characterized by simple operation, but the experimental conditions are stricter, and the selected raw materials must have two groups (hydrophilic group and lipophilic group).
Vapor-phase deposition method-the use of metal compound vapor chemical reaction to synthesize nanomaterials. It is characterized by high product purity and narrow particle size distribution.
Precipitation method–After adding the precipitant to the salt solution to react, heat the precipitation to obtain nanomaterials. Its characteristics are simple and easy to implement, but with low purity and large particle radius.
Hydrothermal synthesis method-synthesis in aqueous solution or steam and other fluids under high temperature and high pressure, and then separate and heat treatment to obtain nanoparticles. It is characterized by high purity, good dispersion, and easy control of particle size.
Sol-gel method-metal compounds are solidified by solution, sol, and gel, and then subjected to low temperature heat treatment to generate nanoparticles. It is characterized by many reaction species, uniform product particles, and easy control of the process.
Microemulsion method–Two immiscible solvents form an emulsion under the action of surfactants, and nano-particles are obtained after nucleation, coalescence, agglomeration and heat treatment in the microbubbles. Its characteristic is the monodispersity of particles and good interface.