Solubilization of Phenol in an Intercalated Surfactant Bilayer

Solubilization of phenol molecules in an intercalated surfactant bilayer, formed within the galleries of an inorganic layered solid, CdPS 3, is reported. The bilayer, formed by grafting of cetyl trimethylammonium (CTA) ions to the internal surface of CdPS 3, functionlizes the surface, converting it from a hydrophilic to a hydrophobic surface. The CTA ions being devoid of functional groups, the interaction between the guest phenol molecules and the methylene chains of the bilayer are dispersive in nature. It is shown that there are two phases of the phenol-solubilized intercalated bilayer, distinguishable by their interlayer lattice spacing and corresponding to solubilized phenol to intercalated CTA ion concentration ratios less than 0.5 and greater. The presence of the guest phenol, which is rotationally mobile, induces conformational disorder in the methylene chains of the intercalated bilayer. The nature and extent of conformational disorder have been studied using infrared and Raman vibrational spectroscopy and 13 C CP-MAS NMR spectroscopy. Conformational disorder in the two phases of the phenol-solubilized bilayer is different, and the observed differences in the interlayer lattice spacings have been related to differences in the nature of conformational disorder.