Effect of aliphatic alcohols and aliphatic carboxylic acids on the critical micelle concentration and counter-ion binding degree of sodium dodecylsulfate

The values of critical micelle concentration and the degree of counter-ion binding of sodium dodecylsulfate (SDS) at the presence of 1-butanol, 1-pentanol, 1-butanoic acid, 1-pentanoic acid and mono-, di- and trichloroacetic acids were determined by electromotive force measurements with dodecylsulfate selective electrode. It was found that aliphatic carboxylic acids have the same effect on micellar properties of SDS as normal alcohols with the same number of carbon atoms. The linear regression of the degree of counter-ion binding on volume fraction of alcohol or carboxylic acid was obtained. Despite the fact that 1-pentanoic and trichloroacetic acid, 1-butanoic and dichloroacetic acid have the similar hydrophobicity, the trichloroacetic acid and dichloroacetic acid affect the micellar properties of SDS to a greater extent than unsubstituted carboxylic acids with 4 or 5 carbon atoms.