Demonstration of maximum solubilization in a polyoxyethylene alkyl ether series of non-ionic surfactants

The solubilization of azobenzene, menaphthone, cortisone acetate, and griseofulvin was measured in a series of non-ionic surfactants of structure CH3[CH2](m-1) [OCH2CH2]1.25m OH, where m varied from 8 to 18. Maximum solubilization occurs when m = 16 (the hexadecyl alkyl ether). This is explained in terms of changes in the oxyethylene mantle close to the micelle core/mantle interface, which appears to be the main locus of solubilization. Micellar properties of CH3[CH2]17[OCH2CH2]22OH are also reported and discussed.