The molecular weight of hydrophobic groups in surfactants is gradually improving

2022-07-25 16:51:16

Generally speaking, the dispersing ability of surfactants depends on the molecular weight and the characteristics of hydrophobic groups. Generally, hydrophobic surfactants with large molecular weight diffuse slowly to the particle surface, but they have strong adsorption ability and are not easy to transfer from the surface, which can provide long-term stability of pesticide formulations. Therefore, the molecular weight of hydrophobic groups in surfactants is gradually improving. 

Therefore, high molecular weight, strong adsorption, strong dispersion and biodegradable substances should be considered when selecting surfactants for pesticide preparations.

China is a large country in the production and use of pesticides. In order to achieve the sustainable development of modern agriculture, the state has successively formulated relevant measures since the tenth five year plan to vigorously reduce or limit the use of some highly toxic pesticides, reduce the proportion of emulsifiable concentrates and wettable powders in pesticide formulations, and develop and promote the production and application technology of new dosage forms. Among them, suspension agents, water emulsions, microemulsions, water dispersible granules and microcapsules are the important development directions today.

Because the processing of most pesticide formulations requires the addition of appropriate surfactants and other additives, in order to improve the performance of pesticides. There are few varieties of surfactants in China, and most of them are relatively old emulsifier varieties. In these new dosage forms, the use of these commonly used surfactants as wetting agents, dispersants, emulsifiers, defoamers and so on can not meet the performance requirements. It is necessary to prepare low toxicity, safe, efficient and environmental friendly surfactants to meet the needs of different pesticide dosage forms processing, so as to develop high-performance Safe special surfactants (surfactants with strong emulsifying ability, good dispersion performance, stronger adsorption capacity and good safety) have become the main direction of research and development of surfactants for pesticides.

At present, these studies mainly focus on polymer surfactants, green surfactants and polymerizable surfactants.

The relative molecular weight of commonly used surfactants is low. When used in water-based formulations of pesticides (such as water emulsion, suspension emulsion, etc.), it will lead to the flocculation and aggregation of particles (or oil droplets) and the increase of adhesion between particles during storage, which can not achieve long-term stable effect, thus reducing the efficacy.