Quaternay ammonium salt bactericide, which has the property of ionic compound, is easy to dissolve in the water while it is hard to behave in the same way in the non-polar solvent, being stable in chemical property. The mechanism of action of this kind of bactericide is the cations to absorb bacteria with negative electricity through electrostatic force, hydrogen bond force and hydrophobic association between molecule of surfactant and protein molecule so as to push the bacteria to get together on the cytoderm and cause lysis and ventricular obstruction, leading to the death of the growth of bacteria due to inhibition. In the meantime, its hydrophobic alkyl group will react with hydrophilic group of bacteria to change the permeability of film, and then lysis happens to make bacteria dissolve and die. This kind of bactericide is high-efficient, non-toxic, no accumulation and moderately poisonous to fish, which is stand still when the pH changes. In addition, it is easy to use and it has rather strong peeling effect with characteristics including stable chemical property, dispersion and good corrosion inhibition.
Since 1935 when cationic surfactant could kill the bacteria, the fourth to sixth generations of quaternay ammonium salt bactericide products have been developed. The first generation was alkyl dimethyl benzyl chloride and HTMAC; the second was the derivatives of the first generation, which was obtained by means of the substitution reactions from bezene ring or quaternary nitrogen of quaternay ammonium salt; the third was dialkyl dimethyl ammonium chloride such as Di-sunflower dimethyl ammonium chloride; the fourth was the compound products of the first and the third generations; the fifth was bisquaternary ammonium salts like ethylene based double( dodecyl dimethyl ammonium bromide) that belonged to Gemini or dimeric surfactant.
Quaternay ammonium salt bactericide not only can kill the bacteria but has strong peeling effect on clay acting as a greenhouse for sulfate reducting bacteria which will be put to death. Also, corrosion inhibition will appear when it is used with other medicament. The common are 1227 ( dodecyl dimethyl benzyl ammonium chloride), 1231( dodecyl trimethyl ammonium chloride), bromo-geramine( dodecyl dimethyl benzyl ammonium bromide), 1427( tetradecyl dimethyl benzyl ammonium chloride), ethylene based double( dodecyl dimethyl ammonium bromide), and ethylene based double( tetradecyl dimethyl ammonium chloride), etc.
Biquaternary ammonium salts contain two hydrophobic groups, two hydrophilic groups and one linking group, whose creative structure will better its properties. The concentration of CMC is low that can lower the surface tension of water efficiently, increase the viscosity of solvent prominently and block the dirt and regulate pH. As for biquaternary ammonium salt, as its molecules become asymmetric, its positive charge gets more collectively and sterilizing effect becomes more ideal. On the contrary, if it is strong in molecular structure, the surface activity rises and the sterilization reduces. Biquaternary ammonium salts has better peeling effect. High-efficient bactericide named MQA made by Nanjing Tech University, Modification of fungicide metronidazole biquaternary ammonium salts named MBQA whose matrix is metronidazole developed by Huazhong University of Science and Technology and the one exploited by Tianjin Institute of Chemical Research and Design are asymmetric biquaternary ammonium salts.