Detailed Explanation Of The Action Principle And Selection Method Of Dispersants

Detailed explanation of the action principle and selection method of dispersants
What is a dispersant - a surfactant that can stabilize the dispersion of solid particles in a solid-liquid suspension in the medium is called a dispersant.
The principle of action of dispersants - dispersion is the process of evenly distributing solid particles in a dispersion, which has a certain degree of stability.
Mainly manifested in:
1. Adsorbed to the surface of solid particles, making the surface of condensed solid particles easy to wet.
2. A polymer type dispersant forms an adsorption layer on the surface of solid particles, increasing the surface charge of solid particles and enhancing the reaction force between particles that form three-dimensional obstacles.
3. The surface of solid particles forms a bimolecular layer structure, and the polar end of the outer dispersant has strong affinity with water, increasing the degree of wetting of solid particles by water. Solid particles move away from each other due to electrostatic repulsion. 4. Make the system uniform, increase suspension performance, and do not precipitate, making the physical and chemical properties of the entire system the same
As mentioned above, the use of dispersants can stably disperse solid particles in liquids.
Dispersant dispersion mechanism
one
Double layer principle - The dispersants used in water-based coatings must be water-soluble and selectively adsorbed onto the interface between the powder and water. Currently, the commonly used type is anionic, which ionizes in water to form anions and has certain surface activity, which is adsorbed on the surface of powders. After the surface of powder particles adsorbs dispersants, a double layer of electricity is formed, and anions are tightly adsorbed on the surface of the particles, known as surface ions. Ions with opposite charges in the medium are called counter ions. They are adsorbed by surface ions through electrostatic adsorption, and some of the counter ions are tightly bound to particles and surface ions, which are called bound counter ions. They become a moving whole in the medium, carrying negative charges, while another part of the counter ions surround them, forming a diffusion layer called free counter ions. This forms a double layer between surface ions and counter ions.