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Synthesis and Characterisation of Organo Phyllosilicates Containing Both Si, Al, and Mg
Published online by Cambridge University Press: 01 February 2011
Abstract
Hybrid materials like organo-phyllosilicates exhibit new properties which make them potential candidates for many industrials applications as rubber reinforcement, environmental barriers…. With this aim, a series of new layered inorganic-organic solids, with organic functionalities directly bonded to the inorganic sheets via the Si-C bond, were prepared by a template sol-gel synthesis under soft conditions (room temperature) using octyltriethoxysilane as the silica source, aluminum acetylacetonate as the alumina source, magnesium nitrate and sodium hydroxide. These hybrid materials belong to the 2:1 trioctahedral phyllosilicates family with inorganic compositions close to saponite. The ratio of Al (x) could be varied between 0 and 0.33. The x-ray diffraction patterns agree with a layers structure (presence of the (00l) peak series and the (060) peak). The high d001 spacing values (2.4-2.6 nm) can be related to the octyl chains present in the interlayer space. DRIFT and 13C NMR spectra indicate that the Si-C bonds are intact and siloxanes are fully hydrolyzed giving SiOAl and SiOMg bonds. 27Al and 29Si NMR were carried out in order to determine the repartition of the different elements in the layer: Al substitutes for Si in the tetrahedral layer and for Mg in the octahedral one. These results were determined by elemental analysis. The DTA-TG results show that the organic matter start to decompose in air above 250°C but its complete removal needs temperatures higher then 800°C. The aspect of the materials depends on the value of x; it varies from greasy, waxy, waxy powdery and finally powdery. The hydrophilicity of the solids depends strongly on the aluminum content.
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- Copyright © Materials Research Society 2002
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