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Covalent Grafting to μ-Hydroxy-Capped Surfaces? : A Kaolinite Case Study

Title data

Hirsemann, Dunja ; Köster, Thomas K.-J. ; Wack, Julia ; van Wüllen, Leo ; Breu, Josef ; Senker, Jürgen:
Covalent Grafting to μ-Hydroxy-Capped Surfaces? : A Kaolinite Case Study.
In: Chemistry of Materials. Vol. 23 (8 June 2011) Issue 13 . - pp. 3152-3158.
ISSN 1520-5002
DOI: https://doi.org/10.1021/cm200235x

Abstract in another language

All μ-hydroxyl groups are frequently encountered capping groups found on the external surfaces of various minerals that are often used as fillers in composite materials. Covalent grafting to this functional group would therefore offer a versatile and attractive route to surface modification. The octahedral layer of kaolinite is composed of μ-bridged aluminol groups. In particular, intercalation compounds of kaolinite, where all basal planes are exposed and may be modified, are ideally suited to study the feasibility of such covalent graftings. The huge (internal) specific surface area greatly improves the sensitivity of the analytics and renders kaolinite an ideal model compound. Herein we analyze the mode of bonding of ethylene glycol (EG), intercalated into kaolinite (EG kaolinite), by solid-state NMR techniques. 27Al MQMAS allows for distinction between intercalated and grafted EG molecules because the chemical surroundings of octahedrally coordinated aluminum nuclei in the layer are significantly changed by the formation of a covalent bond. Moreover, the temperature-dependent dynamics of the EG molecules in the interlamellar space are examined by wide-line solid-state 1H NMR measurements. The EG molecules perform a circular motion around the covalently bonded hydroxyl group in the interlamellar space. Analysis of the 13C–27Al REAPDOR measurement in conjunction with the EG dynamics allows for determination of the 13C···27Al distance between octahedral aluminum and the bonded carbon atom of EG. This distance is 3.1 Å. A thorough description of the bonding mode of the EG molecules is provided and proves beyond any doubt the covalent grafting. This suggests that the reactivity of μ-hydroxyl groups, in general, is sufficient to realize a covalent surface modification of a wide range of minerals.

Further data

Item Type: Article in a journal
Refereed: Yes
Keywords: ethylene glycol intercalated kaolinite; solid-state NMR; covalent grafting; nanocomposites; surface modification; MQMAS; REAPDOR
Institutions of the University: Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry > Chair Anorganic Chemistry I > Chair Anorganic Chemistry I - Univ.-Prof. Dr. Josef Breu
Research Institutions > Collaborative Research Centers, Research Unit > SFB 840 Von partikulären Nanosystemen zur Mesotechnologie
Research Institutions > Collaborative Research Centers, Research Unit > SFB 840 Von partikulären Nanosystemen zur Mesotechnologie > SFB 840 - TP A 6
Research Institutions > Collaborative Research Centers, Research Unit > SFB 840 Von partikulären Nanosystemen zur Mesotechnologie > SFB 840 - TP C 1
Faculties
Faculties > Faculty of Biology, Chemistry and Earth Sciences
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry > Chair Anorganic Chemistry I
Research Institutions
Research Institutions > Collaborative Research Centers, Research Unit
Result of work at the UBT: Yes
DDC Subjects: 500 Science > 540 Chemistry
Date Deposited: 23 Mar 2018 10:47
Last Modified: 23 Mar 2018 10:47
URI: https://eref.uni-bayreuth.de/id/eprint/10454