Abstract
The microenvironments of a series ofpolyfluorinated surfactants [C n F 2 n + 1 CONH(CH 2 ) 2 N + (CH3) 2 C 1 6 H 3 3 Br - ; designated as CnF-S, where n = 1-3]/clay (saponite) hybrid compounds dispersed in water-saturated benzenewere investigated based on the photochemical behavior of Rose Bengal (RB) as a probe molecule. A small-angle X-ray scattering study showed that the interlayer distance (clearance space) of the C3F-S/clay hybrid compounds was expanded up to 3.8 nm by the dispersion in water-saturated benzene from the original distance of 3.0 nm for the dried hybrid compound, indicating expansion of the hybrid compound upon swelling with the solvent benzene. The RB molecules are proposed to form ion-association complexes with the CnF-S surfactant, most likely existing in the vicinity of the ammonium group of the surfactant intercalated in the cation-exchangeable clay saponite. The absorption and fluorescence maxima of RB intercalated in the hybrid compounds were significantly red-shifted from those in aqueous solution. The hybrid compounds provide an environment with polarity between that of ethyl acetate and 1-butanol. The microscopic polarity of the hybrid compounds depends on the fluorocarbon chain length (n) of the surfactant, and the polarities increase with increasing fluorocarbon chain length. On the basis of the observed photochemical behavior of RB, including the relative decomposition rates, excited triplet lifetimes, and relative excited triplet quantum yields, the microscopic concentration of water in the hybrid layer was estimated to decrease in the order C3F-S > C2F-S > C1F-S. These differences are discussed in relation to differences in the microscopic orientational structure of the polyfluorinated surfactant within the clay layer.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.