Surface-tension properties of some polydispersed alkyl-substituted polyoxyethylated phenylsulfonamides

Twenty-nine laboratory-prepared polydisperse nonionic surfactants, derived from polyoxyethylated N-alkylphenylsulfonamides [R phi SO2N(R') (EO)(n)H], have been characterized. EO is ethyoxylation; R is hydrogen, n-butyl or t-butyl; R' is hexyl, octyl, or decyl; and (EO)(n) is varied from (EO)(4) to (EO)(20). Surface tension in aqueous solution was studied. The critical micelle concentration, surface excess, minimum area per molecule, effectiveness of surface-tension reduction, and free energy of micelle formation were calculated from the surface-tension measurements. The critical micelle concentrations for the derivatives in which R' = hexyl were considerably higher than the corresponding derivatives where R' is octyl or decyl. The greatest surface-tension reduction was found in the R' = n-octyl derivatives where R is t-butyl with (EO)(9) or n-butyl with (EO)(11).