Universität zu Köln

Kensbock, Philip, Demco, Dan Eugen, Singh, Smriti, Rahimi, Khosrow, Fechete, Radu, Walther, Andreas, Schmidt, Annette Monika and Moeller, Martin (2017). Peptizing Mechanism at the Molecular Level of Laponite Nanoclay Gels. Langmuir, 33 (1). S. 66 - 75. WASHINGTON: AMER CHEMICAL SOC. ISSN 0743-7463

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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 by P-31 and H-1 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. P-31 HRNMR spectroscopy on sodium fluorohectorite with an aspect ratio of similar to 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.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Kensbock, Philip UNSPECIFIED UNSPECIFIED UNSPECIFIED Demco, Dan Eugen UNSPECIFIED UNSPECIFIED UNSPECIFIED Singh, Smriti UNSPECIFIED UNSPECIFIED UNSPECIFIED Rahimi, Khosrow UNSPECIFIED UNSPECIFIED UNSPECIFIED Fechete, Radu UNSPECIFIED UNSPECIFIED UNSPECIFIED Walther, Andreas UNSPECIFIED UNSPECIFIED UNSPECIFIED Schmidt, Annette Monika UNSPECIFIED UNSPECIFIED UNSPECIFIED Moeller, Martin UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-242600
DOI:	10.1021/acs.langmuir.6b03592
Journal or Publication Title:	Langmuir
Volume:	33
Number:	1
Page Range:	S. 66 - 75
Date:	2017
Publisher:	AMER CHEMICAL SOC
Place of Publication:	WASHINGTON
ISSN:	0743-7463
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language AQUEOUS DISPERSIONS; SPECTROSCOPY; SUSPENSIONS; GELATION; SURFACE; PH Multiple languages Chemistry, Multidisciplinary; Chemistry, Physical; Materials Science, Multidisciplinary Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/24260