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1. Random polymeric surfactant
This kind of surfactant is a polymer surfactant with a three-dimensional network structure formed by polymerization of polyalkylene diols, polyols and fatty or aromatic polycarboxylic acids and their anhydrides. For example Atlox49.4(HLB=6), the hydrophilic action is provided by many ester or ether groups. When it is used in combination with an A-B or A-B-A copolymer with A high HLB value, good stability of O/W emulsions can be obtained.
2. Programmed polymeric surfactants
This class refers to the polymeric surfactant of A-B-A block copolymer, typically in the form of EO-PO-EO block copolymer, which is commonly used as an emulsifier and dispersant for pesticides. There are still some shortcomings in the use of water-based formulations, mainly that it often falls off the adsorption surface and the solubility of EO units depends on the ionic strength and temperature of the medium; Another disadvantage is that PO has A low solubility in hydrocarbons, especially in fatty hydrocarbons, but can be adjusted by choosing different A and B to obtain a block copolymer with good performance. Atlox4912, for example, is an A-B-A block copolymer made from poly (12-hydroxy-stearic acid) esterified with poly (alkylene) diol. This surfactant is well suited for use as a pesticide emulsifier and stabilizes O/W emulsions well when combined with an emulsifier with a high HLB value. The oleophilic chain in this emulsion plays an adsorption role and enters the oil phase, while the hydrophilic polyethylene glycol with high relative molecular weight provides water phase stability, and the determination of the oleophilic chain into the oil is several times more than the commonly used C18 dehydrated sorbitan ester, that is, the adsorption capacity is stronger.
3. Comb-type graft polymerization surfactant
These surfactants have a very high relative molecular mass, with an average relative molecular mass between 20,000 and 30,000. It has a very long oleophilic main chain as the skeleton to ensure that it can strongly adsorb on the surface of the particle without falling off and transferring; The hydrophilic chain connected with the main chain extends into the water phase like a tooth to ensure the special steric hindrance. Taking Atlox4913 as an example, it uses the copolymer of polymethacrylate/methacrylate to form the backbone of the main chain, which plays an adsorption role, and the polyoxyethylene chain of appropriate length as the oil-wet part extends into the water phase around the particle to play a barrier steric effect. The adsorption capacity of this polymer surfactant is 10 times larger than that of commonly used surfactants, and it is almost difficult to fall off and transfer from the particle surface. It is used as a pesticide dispersant to improve the heat storage stability of the preparation, and can also be used to prepare high concentration water suspension in pesticides.