Synthesis of nonionic surfactants DL-α-tocopherol methoxypolyethylene glycol succinates and their applications in pesticide formulations
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Abstract
The nonionic surfactants DL-α-tocopherol methoxypolyethylene glycol succinates (TPGS-X-M, X represents the molecular weight of methoxypolyethylene glycols used and X is 750, 1000, 1500 or 1900) have been efficiently synthesized using DL-α-tocopherol as the hydrophobic end and polyethylene glycol(EO) as the hydrophilic end. Critical micelle concentrations (cmc), and the static and dynamic surface tensions of these four surfactants have been measured. These surfactants were used as dispersing agents in 20% etoxazole suspension formulation. The resulting dispersions were compared with the commercial dispersant FS3000 in various physical and chemical parameters. The static surface tensions of the surfactants indicated that the length of polyoxyethylene ether chain had little influence on the critical micelle concentrations of the surfactants. The results of dynamic surface tension tests showed that the surfactants TPGS-1000-M, TPGS-1500-M and TPGS-1900-M had a greater downward trend than that of FS3000 at 1 249.3 ms, which exhibited some advantages. The surfactants TPGS-1500-M and TPGS-1900-M were used as dispersing agents in 20% etoxazole suspension formulation for the test of their particle sizes, suspension rates, active ingredient contents, suspensibilities, thermal storage stabilities and low temperature stabilities. The results revealed that the suspension effects of new surfactants TPGS-1500-M and TPGS-1900-M were similar to that of FS3000 suspending agent. Therefore, surfactants TPGS-1500-M and TPGS-1900-M could be used as dispersing agents for suspension formulations.
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