Effect of binary solvents on the critical micelles concentration by using 1-methyl-4-[4′-aminostyryl]pyridinium iodide

The influence of preferential solvation of 1-methyl-4-[4′-aminostyryl]pyridinium iodide (M-NH2) on critical micelles concentration (c.m.c) has been studied by using sodium dodecyl sulfate (SDS) in the binary aqueous mixtures of protic and aprotic co-solvents including glycerol, ethylene glycol, dimethyl sulfoxide (DMSO), and acetone. The results reveal that the c.m.c depends on the polarity, in addition to the dielectric constant of the co-solvents. The lower the polarity as well the dielectric constant (ε), the more effective the breaking of the micelles. Acetone which has a low polarity (Z), low dielectric constant (ε), and large hydrophobic surface is shown to be the strongest denaturant for micelles. On the other hand DMSO, which has relative hydrophobic effect with large (ε), in addition with glycerol and ethylene glycol which has large (ε) and small hydrophobic surface have the weakest effect.