Investigation of the structure and dynamics of surfactant molecules in mesophase silicates using solid-state {sup 13}C NMR
- Pacific Northwest National Lab., Richland, WA (United States)
The structure and dynamics of surfactant molecule reorganization in mesophase silicates have been investigated using variable-temperature {sup 13}C solid-state nuclear magnetic resonance (NMR) spectroscopy. Functional groups and side groups of the surfactant CTAC (cetyltrimethylammonium chloride) were identified from high-resolution {sup 13}C MAS (magic angle spinning) NMR spectra obtained using high-power {sup 1}H decoupling. We also obtained information on surfactant organization and relaxation in mesophase silicates using a combination of NMR line-shape and relaxation-time analyses with variable-temperature NMR. The behavior of the surfactant in the ordered mesophase silicate was compared with that of the surfactant solution (CTAC-water) and that of the surfactant in the disordered silicate, which was precipitated in solution during an early stage of the reaction. The splitting of the resonance associated with the N-methyl groups suggests that the methyl groups next to the head group lose their stereochemical symmetry due to the intermolecular interaction in the ordered mesophase silicates. For both ordered and disordered silicates, the methylene group adjacent to the head group exhibits a marked lack of motion relative to other segments of the surfactant. Variable-temperature NMR studies show motional narrowing as temperature increases. 17 refs., 9 figs., 2 tabs.
- OSTI ID:
- 264050
- Journal Information:
- Langmuir, Journal Name: Langmuir Journal Issue: 11 Vol. 12; ISSN LANGD5; ISSN 0743-7463
- Country of Publication:
- United States
- Language:
- English
Similar Records
Study of Local Molecular Ordering in Layered Surfactant-silicate Mesophase Composites
Study of Local Molecular Ordering in Layered Surfactant-Silicate Mesophase Composites