Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Google Scholar Articles by GERSTMANS, A. Articles by GRANDJEAN, J. GeoRef GeoRef Citation

XRD and NMR characterization of synthetic hectorites and the corresponding surfactant-exchanged clays

¹ COSM, University of Liège, Institute of Chemistry B6a, Sart-Tilman, B-4000-Liège, Belgium, ² CERM, University of Liège, Institute of Chemistry B6a, Sart-Tilman, B-4000-Liège, Belgium, and ³ IMPMC Campus Boucicaut, 140 rue de Lourmel, F-75015 Paris, France

^* E-mail: J.Grandjean{at}ulg.ac.be

(Received 25 April 2007; revised 19 November 2007)

Synthetic hectorites and the corresponding surfactant-exchanged clays have been characterized by X-ray diffraction and ¹H, ⁷Li, ¹³C, ²³Na and ²⁹Si solid-state nuclear magnetic resonance (NMR) spectroscopy. The low-charge clays retain water more efficiently, forming aggregates without extensive drying. The hydroxylated hectorite exhibits two ¹H NMR signals near 0 ppm whereas the fluorohectorites are characterized by a single peak in the same region. The ²³Na 2D 3Q magic angle spinning (MAS) spectra of the low-charge hectorites show a single peak. The ²⁹Si NMR shift depends on the interlayer charge. Tactoids formed by the low-charge hectorites reduce the rate of surfactant incorporation. The population of the all-trans conformer of the hydrocarbon chain, determined by ¹³C MASNMR, varies with the surfactant content. ¹³C NMR relaxation data show an increase in mobility with the surfactant loading and along the long alkyl chain, from the polar head to the terminal group. Complexity of the motional behaviour precludes any detailed analysis. These modified clays are not useful in preparing poly(-caprolactone) nanocomposites by in situ polymerization.

KEYWORDS: MAS NMR, XRD, hectorite