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Abstract Contradictory literature references on their micelle formation led to an investigation of block copolymers of ethylene and propylene oxides. By means of differential absorbance measurements of the dye‐surfactant complex, critical micelle concentrations (CMC舗s) for these polyols were determined. CMC values for surfactants with a molecular weight range of 1,100 to over 15,000 varied from 3.0 to 11.1 Ɓmoles per liter, which are much lower than for other nonionics normally encountered. Corroborative data were obtained by the surface tension depression method. An increase in temperature below the cloud point or the addition of sodium chloride resulted in an increase in the CMC, which is not usual for many nonionics.
Schmolka et al. (Wed,) studied this question.