title: Peptizing Mechanism at the Molecular Level of Laponite Nanoclay Gels.
abstract: In the presence of additives such as etidronic acid (1-hydroxyethane-1,1-diphosphonic acid, HEDP), a process of peptizing of Laponite clay gels takes place. The peptizing process at the molecular level was directly revealed by31P and1H high-resolution magic-angle sample spinning (HRMAS) NMR spectroscopy. Two NMR spectral components were detected and assigned to free etidronic acid and bound to the Laponite disk edges. Furthermore, with increase of temperature the ratio of bound-to-free etidronic acid increases. This thermal activation process could be explained by the increase in electrical polarization of the hydroxyl group at the edges and by the exfoliation of the tactoids that leads to more access to the additive molecules to the electrical charges of platelet edges.31P HRNMR spectroscopy on sodium fluorohectorite with an aspect ratio of ∼750 shows a reduction of the bound etidronic acid molecules. Transmission electron microscopy (TEM), field-emission scanning microscopy (FESEM), UV-vis spectrophotometry, dynamic light scattering (DLS), and zeta potential results support the proposed peptizing mechanisms.
authors.affiliation: DWI-Leibniz-Institute for Interactive Materials, e.V., RWTH-Aachen University , Forckenbeckstraße 50, D-52074 Aachen, Germany.
authors.forename: Philip
authors.initials: P
authors.lastname: Kensbock
authors.affiliation: DWI-Leibniz-Institute for Interactive Materials, e.V., RWTH-Aachen University , Forckenbeckstraße 50, D-52074 Aachen, Germany.|Institute of Physical Chemistry, University of Köln , Luxemburger Str. 116, D-50939 Köln, Germany.
authors.forename: Dan Eugen
authors.identifier: 0000-0003-0217-5456
authors.initials: DE
authors.lastname: Demco
authors.affiliation: DWI-Leibniz-Institute for Interactive Materials, e.V., RWTH-Aachen University , Forckenbeckstraße 50, D-52074 Aachen, Germany.
authors.forename: Smriti
authors.initials: S
authors.lastname: Singh
authors.affiliation: DWI-Leibniz-Institute for Interactive Materials, e.V., RWTH-Aachen University , Forckenbeckstraße 50, D-52074 Aachen, Germany.
authors.forename: Khosrow
authors.initials: K
authors.lastname: Rahimi
authors.affiliation: Department of Physics and Chemistry, Technical University of Cluj-Napoca , 25 G. Baritiu Str., RO-400027, Cluj-Napoca, Romania.
authors.forename: Radu
authors.initials: R
authors.lastname: Fechete
authors.affiliation: DWI-Leibniz-Institute for Interactive Materials, e.V., RWTH-Aachen University , Forckenbeckstraße 50, D-52074 Aachen, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Walther
authors.affiliation: Institute of Physical Chemistry, University of Köln , Luxemburger Str. 116, D-50939 Köln, Germany.
authors.forename: Annette Monika
authors.initials: AM
authors.lastname: Schmidt
authors.affiliation: DWI-Leibniz-Institute for Interactive Materials, e.V., RWTH-Aachen University , Forckenbeckstraße 50, D-52074 Aachen, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Möller