Emulsion, oil in water (EW) formulations are used in the crop protection industry to formulate oily or low melting point active ingredients with minimum or no addition of solvent to improve handling and environmental profile. Approaches to stabilize EW formulations generally attempt to induce repulsion between droplets by electrostatic or steric means by the use of non-ionic, polymeric or block copolymer surfactants. Physical instability may include creaming, sedimentation, flocculation, coalescence, Ostwald ripening, syneresis (phase separation) or crystallization.<br/><br/>The use of two block copolymer surfactants comprised of strong anchoring hydrophobic groups and ethylene oxide hydrophilic chains, often provide good steric stabilization over a diverse range of expected storage conditions.<br/><br/>A case study EW type agrochemical formulation stabilized by an n-butanol EO-PO block copolymer and an A-B-A block copolymer of poly 12-hydroxy stearic acid (pHSA) copolymerized with polyethylene glycol (PEG), is used in this study to investigate the effect of the structure and physical-chemical properties of the polymeric surfactants on the physical stability of the EW with respect to syneresis and emulsion droplet size stability during accelerated storage testing.

Influence of polymeric surfactant structure and physical-chemical properties on the physical stability of an oil in water emulsion type agrochemical formulation

254th National Meeting (2017)

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