Volume 7, Issue 6 (June 2010)
EW Formulations Using Polymeric Surfactants
Four polymeric surfactants of consistent chemistry with different architectures were evaluated in concentrated emulsions, also known as emulsions in water (EW), of 2,4-dichlorophenoxyacetic acid, 2-ethylhexyl ester (2,4-D ester). EW dilution performance was evaluated using the ASTM E1116-98 standard emulsion test, and the emulsion was analyzed for droplet size distribution using a light scattering technique; zeta potential was determined, and rheology measured. A structure-property-performance relationship for these polymeric surfactants in the subject EW was developed. All four polymeric surfactants proved to be effective in formulating stable EWs with the corresponding emulsion stability increasing positively in the order of random, triblock, quasi-diblock, and finally diblock. Preferred polymeric surfactant performance in EW provided small droplet sizes with excellent dilution stability due primarily to the steric stabilization of the dispersed phase in both the concentrates and upon dilution.