What Are Wetting Agents?

A substance that makes solid materials more susceptible to wetting by water. By reducing its surface tension or interfacial tension, water can spread on the surface of the solid material, or penetrate into the surface, thereby wetting the solid material.

moisturizer

A substance that makes solid materials more susceptible to wetting by water. By lowering it

Wetting agents are substances that make solid materials more easily wetted by water by reducing their surface energy

Water droplets spread out into a thin layer on clean glass, while drops on glass coated with wax are called spheres. The former is called

Water can soak the glass because the silicates of the glass are polar materials, and the interaction between them is strong and can be close to each other to reduce the surface energy of water. Water cannot be wet because wax is a non-polar substance. The force between them is weak and cannot be close to each other to reduce the surface energy of water. When the surface energy is high, the water automatically shrinks into a sphere.

Wetting agent belongs to

When the pesticide is a hydrophobic solid powder, its surface is not easily wetted by water, and it is difficult to dissolve in water to sink and agglomerate. If a wetting agent is added, since the wetting molecules are aligned on the surface of the solid, the surface energy of the water is reduced, the water can wet the solids, and the solid powder is dispersed in water to become a stable suspension. Another example is that wax is present on the leaves of plants and insects. The spray of the liquid medicine is because it cannot be wetted, and it becomes a spherical roll-down or the water is volatilized to form it. In order to make the medicinal solution have good wetting properties, it is spread on the leaves of plants and insects, in order to give full effect, wetting agents are often added to pesticides. The wetting effect is more practical in chemical experiments. After the experiment, the glass instruments must be washed. The wall of the cleaned glass instrument should be covered with a thin and even water film without hanging water drops. If there are drops of water on the glassware, the oil is not clean and must be washed again. ^[2]

In general, for drugs that are not very hydrophobic, ethanol, propylene glycol, glycerin, etc. are usually ground to achieve wetting. For drugs or medicinal materials that are highly hydrophobic, surfaces with HLB values between 6 and 15 are generally used Active agent. You can also choose from any of the following indicators:

Wetting agent contact angle

Contact angles: The angle between the droplet and the spreading surface. The selected wetting agent should reduce the contact angle of the hydrophobic drug to less than

90 °. When the contact angle is 0, it can be completely wet; when the contact angle is 0 to 90 °, it can be wet and is a hydrophilic drug; when the contact angle is greater than 90 ° and less than 180 °, it cannot be wet; when the contact angle is 180 ° It is completely non-wetting and is a hydrophobic drug.

Wetting agent interfacial tension

Interfacial tensions: Some wetting agents change the interfacial tension between hydrophobic drugs and solvents.

Wetting agent wetting amount

Wetting point: Wetting point refers to the amount of solvent needed to make 100g of hydrophobic drug just wet. Adding a wetting agent can reduce the wetting point, that is, reduce the amount of solvent.