Published: Jan 2003
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Structured Surfactant Formulations (SSF) are close-packed three-dimensional matrices of a liquid crystalline phase that suspend insoluble pesticide materials. The active ingredient can be either solid or liquid. Additional actives and/or adjuvants can be dissolved or suspended in the formulation if desired. The main advantage of an SSF over standard formulation alternatives is that no thickening or suspending agents are required. The SSF formulation can be solvent-free if desired, or include an oil adjuvant.
A brief introduction on surfactant phase behavior will be presented as background material. When the surfactant loading in aqueous solutions reaches high levels the surfactants begin to associate in liquid crystalline phases. Liquid crystalline phases can also be formed at low surfactant concentration by a technique known as salting out. This phase behavior can be exploited by suspending dispersions of pesticide active ingredients using economical levels of surfactant. A typical SSF contains from 0–60 w/w% active, surfactants for wetting and dispersing as well as structuring, and finally antifreeze and antifoam, if required. The typical properties of an SSF are excellent concentrate physical stability, relatively low viscosity (after the yield stress is overcome), good storage stability, good wetting, and the ability to form stable suspensions on dilution in the spray tank.
SSF technology can be applied to a wide range of pesticide materials, including herbicides, fungicides, and insecticides. The development of an herbicide SSF is presented that demonstrates how surfactant chemistry can be used to optimize the formulation efficacy. Combination packs that include both water-soluble and water-insoluble actives are also presented. Formulation adjuvants such as oils or electrolytes can also be incorporated into an SSF formulation to increase its biological activity.
agricultural formulation, surfactant, structured surfactant, liquid crystal, spherulite, linear alkylbenzene sulfonate, alcohol ethoxylate, suspension concentrate
Technical Manager, Agrochemicals, Huntsman Surface Sciences Americas, Austin, TX
Technical Marketing Manager, Huntsman Surface Sciences Europe, Saint — Mihiel,
Chemist, Huntsman Surface Sciences Europe, Oldbury, West Midlands
Marketing Manager, Huntsman Surface Sciences Europe, Saint — Mihiel,