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What are the structures of the organosilicon surfactants

Mar 31, 2018

What are the structures of the organosilicon surfactants

The organosilicon surface active T type structure with organosilicon is used for pesticide auxiliaries, with all the skeleton composed of methylsiloxane, which draped over one or more polyether chain segments from the skeleton. The general formula of chemical structure (1):

The hydrophobicity of the skeleton and the flexural property of the main chain make the methyl contact at the interface. The hydrophobicity of methyl is stronger than that of methylene, and methylene is the main body of most commonly used hydrophobic parts of non-ionic hydrocarbon surfactants.

The hydrophilic part of the organosilicon surfactant, similar to most commonly used nonionic surfactants, is a chain with a self loosely distributed range of polyethoxyl alkyl (EO) units. The hydrophilicity by isopropoxides block very small (PO) unit and ease. The total polarity of surfactants can be regulated by the ratio of two methyl siloxane units.

Stability of 2 organosilicon surfactants

Silicon oxygen bonds in silicone frameworks are sensitive to hydrolytic cracking.  Hydrolysis is catalyzed by various factors, but the most important factor in agricultural application is pH value and time.

Under the condition of neutral (pH value 6--8), the long-term stability of the hydrolysate is good; the activity of 5~6 or 8~9 of the solution for the night is not significantly reduced, and it must be applied immediately under the condition of acid PH<5 or alkaline PH>9. Under extreme pH conditions, when sprayed with some growth regulators, the solution will rapidly hydrolyze and reduce its efficacy.

The hydrolysis of siloxane in acid or alkaline conditions may be due to the rearrangement of molecules, the combination of 2 three siloxane copolymers, and the formation of four siloxane and six methyl two siloxane. Three formula for siloxane reaction (2):

The ratio of siloxane and polyether to 4:2 is four, while in three siloxane, the ratio is 3:1. The rearrangement reaction will greatly increase the content of polysiloxane copolymers, thus greatly reducing the surface activity.

Organosilicon rearrangement occurs under the action of acid and alkali, so it is at point.

As a pesticide additive, it will be limited, but it may also be an important name, composition and performance indicator in Table 1 from the point of view of the commercial protection of organosilicon surfactants for common pesticide additives in the environment.

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