Complex formation between polyethylene oxide-containing nonionic surfactants and α- and β-cyclodextrins

The inclusion complexes based on polyethylene oxide (PEO)-containing nonionic surfactants and α(β)-cyclodextrins (CD) were synthesized. Their composition and crystal structure were studied. The inclusion complexes of the surfactants with α-CD form a crystal structure similar to that of the α-CD—PEO complex. The inclusion complexes of the nonionic surfactants with β-CD form a structure similar to that of the β-CD—PEO complex. The structural models of the crystalline complexes were proposed. The micelle-forming abilities of the surfactants in dilute solutions in the presence of CD were studied. The CD binding to a surfactant molecule in aqueous solutions begins from the PEO fragment. Possible reasons for the formation of inclusion complexes between noncomplementary surfactant and β-CD molecules were discussed. The thermal stability was studied, and the possibility of thermal dissociation of the pseudo-complementary β-CD—surfactant complexes was shown.