Functionalization of synthetic talc-like phyllosilicates by alkoxyorganosilane grafting

Karine Chabrol; Marie Gressier; Nadine Pebere; Marie-Joëlle Menu; François Martin; Jean-Pierre Bonino; Claire Marichal; Jocelyne Brendle

doi:10.1039/C0JM01276A

Functionalization of synthetic talc-like phyllosilicates by alkoxyorganosilane grafting

Karine Chabrol,^ab Marie Gressier,*^a Nadine Pebere,^b Marie-Joëlle Menu,^a François Martin,^c Jean-Pierre Bonino,^a Claire Marichal^d and Jocelyne Brendle^d

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* Corresponding authors

^a Université de Toulouse, Institut Carnot CIRIMAT, UMR 5085 UPS/INPT/CNRS, Université Paul Sabatier, 118 route de Narbonne, Toulouse cedex 9, France
E-mail: gressier@chimie.ups-tlse.fr
Fax: (+33)561556163
Tel: (+33)561556120

^b Université de Toulouse, Institut Carnot CIRIMAT, UMR 5085 UPS/INPT/CNRS, ENSIACET, 4 allée Emile Monso, BP 44362, Toulouse cedex 4, France

^c Laboratoire des Mécanismes et Transferts en Géologie, UMR 5563 UR 154 CNRS, Université Paul Sabatier IRD Observatoire Midi-Pyrénées, 14 avenue Edouard Belin, Toulouse, France

^d Equipe Matériaux à Porosité Contrôlée, Institut de Science des Matériaux de Mulhouse, LRC CNRS 7228, Université de Haute Alsace, 3, rue A. Werner, Mulhouse, France

Abstract

A range of talc-like phyllosilicates were prepared via a hydrothermal synthesis performed at five different temperatures from 160 to 350 °C. The organization of the lattice and the degree of crystallinity of the new materials were evaluated by different techniques such as XRD, FTIR, solid-state ²⁹Si NMR, TEM, FEG-SEM and TG-DTA. When synthesized at low temperature the material presents high degree of hydration, low crystallinity and flawed structure. This was attributed to stevensite-talc interstratified product present in the samples. The stevensite/talc ratio and the hydration decrease in the talc-like phyllosilicate samples when the hydrothermal synthesis temperature increases and so the crystallinity becomes higher. A thermal treatment at 500 °C allowed a significant flaw reduction in talc-like phyllosilicate structure; the synthesized sample at 350 °C and heat treated presents a structure close to that of talc. The different talc-like phyllosilicates were grafted covalently by two organoalkoxysilane reagents, N-(3-triethoxysilylpropyl)-4,5-dihydroimidazole (IM2H) and 2-hydroxy-4-(3-triethoxysilylpropoxy)-diphenylketone (HTDK). The grafted amounts of the hybrids, determined by elemental analysis and confirmed by thermogravimetric data, are dependent on the hydrothermal synthesis temperature and organoalkoxysilanes; they become smaller when the synthesis temperature increases and when HTDK is used. FTIR and solid-state ¹³C CP MAS NMR were applied to characterize the grafted organic groups. So, in this work it is shown that by choosing the hydrothermal synthesis temperature or by performing an additional annealing it is possible to adjust the amount of defects in the structure of talc-like phyllosilicates which seems to be strongly correlated to the grafting performance.

Journal of Materials Chemistry

Functionalization of synthetic talc-like phyllosilicates by alkoxyorganosilane grafting

Abstract

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Functionalization of synthetic talc-like phyllosilicates by alkoxyorganosilane grafting

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