What is fluorosurfactant
fluorosurfactant is a surfactant with a fluorocarbon chain as a non-polar group, that is, a fluorine atom partially or completely replaces the hydrogen atoms on the hydrocarbon chain. Fluorocarbon surfactants have high surface activity, high thermodynamic and chemical stability. As we all know, surfactants are generally composed of polar groups (hydrophilic groups) and non-polar groups (hydrophobic groups). The non-polar groups of ordinary surfactants are hydrocarbon chains, while the non-polar groups of fluorocarbon surfactants are fluorocarbon chains, that is, fluorine atoms partially or completely replace the hydrogen atoms on the hydrocarbon chain. However, there is no obvious difference between the two in the structure of polar groups. Therefore, fluorocarbon surfactants are surfactants that replace hydrocarbon chains with fluorocarbon chains as non-polar groups in the molecule. However, it has many properties that ordinary surfactants do not have or have better, which has attracted people's attention and has shown more and more vitality. .
Like ordinary surfactants, fluorocarbon surfactants can be classified into two categories: ionic and non-ionic according to their different polar group structures. Ionic can be divided into anionic, cationic and zwitterionic fluorocarbon surfactants.
1. Anionic fluorocarbon surfactant:
According to their polar groups (hydrophilic groups), they can be divided into carboxylates (RfCOO-M), sulfonates (RfSO3-M), phosphates (RfOPO3M) and sulfates (RfOSO3-M) , the first three are mainly used in industry.
Carboxylate fluorocarbon surfactants: generally have low solubility in strong acids or aqueous solutions containing high-valent cations, but have high thermal stability;
Sulfonate fluorocarbon surfactants: relatively better oxidation resistance, less sensitivity to strong acids and electrolytes;
Phosphate fluorocarbon surfactants: Relatively poor foaming performance.
2. Cationic fluorocarbon surfactant:
Cationic fluorocarbon surfactants are almost all nitrogen-containing compounds, namely organic amine derivatives. Since the surface particles of most substances are negatively charged, cationic active agents are easily adsorbed.
3. Zwitterionic fluorocarbon surfactants:
The molecular structure of zwitterionic activator contains both acidic and basic groups, and the ionic type it exhibits depends on the pH value of the solution, that is, it is cationic in acidic medium and anionic in alkaline medium. The acidic groups of amphoteric fluorocarbon surfactants are mainly carboxylic acid groups and sulfonic acid groups, and the basic groups are mainly amino groups or quaternary ammonium groups. Amphoteric fluorocarbon surfactants have excellent emulsifying properties and are used as emulsifiers in the manufacturing process of fluorocarbon materials, paper, leather and other products.
4. Non-ionic fluorocarbon surfactants:
Non-ionic fluorocarbon surfactants are not ionized in aqueous solution, and their polar groups are usually oxygen-containing ether bonds (such as polyoxyethylene). Nonionics are more soluble in water and organic solvents (including acid and alkaline media) than other types of active agents, and have better compatibility with other types of active agents. Because it is not ionized in water, it has high stability to pH value and is less affected by electrolytes and inorganic salts. However, because its polar group is composed of a certain number of oxygen-containing ether bonds/hydroxyl groups, it cannot be used in strong oxidizing media. , so as not to cause the breakage of the ether bond.
