INTERACTIONS OF BETA-CYCLODEXTRIN WITH 4-ALKYLMORPHOLINE N-OXIDE SURFACTANTS

Interactions of beta-cyclodextrin (CD) with nonionic surfactants of th e 4-alkylmorpholine N-oxide type (alkyl = C-9-C-16) in aqueous solutio ns were investigated using the spectrophotometric method with methyl o range and the solubilization method, respectively. Results from both t he methods confirmed that the process of surfactant association in aqu eous solutions is affected by the formation of water-soluble CD surfac tant inclusion complexes. In the presence of CD each phase of this pro cess (i.e. monomers, fractional micelle formation range, micellar zone ) is shifted towards higher surfactant concentrations. The ratio DELTA CMC/c(CD) expressing the measure of the CD surfactant interaction decr eases with prolongation of the alkyl chain. It seems that the CD inter acts with the alkyl chain of the surfactant molecule and not with its polar head group.