silicone surfactants are a type of surfactant composed of polydimethylsiloxane as its hydrophobic backbone and one or more organic silicon polar groups connected to the meta or terminal positions. According to the chemical properties of the hydrophilic group R in its chemical structure, silicone surfactants can be divided into four categories: anionic, cationic, nonionic, and zwitterionic. Among them, nonionic surfactants are the most studied. , The most widely used.
1. Cationic silicone surfactant
If the R group contains structural units such as alkyl quaternary ammonium compounds, amido quaternary ammonium compounds and imidazoline derivative quaternary ammonium compounds, it is called a cationic silicone surfactant. Among cationic silicone surfactants, cationic polysiloxane quaternary ammonium salt surfactants are the most widely used. The cationic polysiloxane quaternary ammonium salt surfactant has a large molar mass and can be compatible with anionic surfactants. It has no irritation to human skin and eyes. It has a certain antibacterial ability. It does not produce free ammonium in alkaline solution. stable. The macromolecule of this product contains hydrophobic long-chain polysiloxane chain, which makes it have excellent smoothness and softness.
2. Anionic silicone surfactant
When the R group contains structural units such as phosphate, sulfate, carboxylate, sulfonate and sulfosuccinamide ester, it is called an anionic silicone surfactant. When R is the structure shown in the figure below, it is called anionic polysiloxane phosphate salt surfactant.
When R'is a fatty acid functional group, it is a polysiloxane phosphate betaine amphoteric surfactant. The surfactant molecule not only has the structure and characteristics of phosphate betaine, but also has the structure and characteristics of polysiloxane. If a low molar mass polysilane is selected, the polysiloxane has weak properties; on the contrary, if a large molar mass polysiloxane is selected, the polysiloxane has significant properties. This kind of product has the characteristics of low toxicity, antibacterial, hard water resistance, and good compatibility with various surfactants.
3. Non-ionic silicone surfactant
When the R group contains units such as polyether, alkanolamide, ester, glycoside, etc., it is nonionic surfactant. Among them, polyether silicone surfactants are the most widely used.
Non-ionic polyether silicone surfactant is a combination of polysiloxane segment (A) and polyether segment (B). The combination methods are: AB type, ABA type, BAB type, (AB) Types such as n-type, branch-chain type and side-chain type. There are two ways to connect the polyether segment and the siloxane segment, namely the Si-O-C type and the Si-C type. The former is unstable and belongs to the hydrolyzed type; the latter is stable to water and is called the non-hydrolyzed type.
4. Amphoteric silicone surfactant
If the R group contains structures such as phosphate betaine or betaine, it is called an amphoteric polysiloxane surfactant.