Structures, Electronic Properties, and Interactions of Cetyl Alcohol with Cetomacrogol and Water: Insights from Quantum Chemical Calculations and Experimental Investigations

The complexes of cetyl alcohol, cetomacrogol-1000, and water were successfully synthesized. The complexes were characterized by freeze-drying scanning electron microscopy, small-angle X-ray diffraction (SAXD), and ultra-SAXD. Furthermore, structures, electronic properties (the HOMO-LUMO gap, ionization potential, electron affinity, electronegativity, hardness, softness, dipole moment, and polarizability), and Raman spectra of cetyl alcohol, cetomacrogol-1000, and their binary and ternary complexes with water were also studied using density functional theory. The calculated lengths of hydrophilic heads in the ternary complexes were in good agreement with SAXD data. The results indicated the existence of two types of interlamellar spacings between successive swollen bilayers (approximately 144 and 72 A) when polyoxyethylene groups of cetomacrogol-1000 molecules were completely hydrated and stretched. Besides, in comparison with the monomers, the ternary complex of cetyl alcohol, cetomacrogol-1000, and water with the molecular ratio of 1:1:1 (cetyl-ceto-H2O-1 complex) had outstanding properties.