A new Al,Mg-organoclay

Abstract

A new inorganic–organic solid, with a 2∶1 phyllosilicate layer structure and octyl chains directly bound to the inorganic sheets via Si–C covalent bonds, was prepared at room temperature from an ethanolic gel with the molar composition RSiO_3/2 ∶ 0.255 Al₂O₃ ∶ 0.5 MgO ∶ 130 CH₃CH₂OH ∶ 0.62 Na₂O. Octyltriethoxysilane was used as the silica source. The introduction of octyl chains in the interlayer space was confirmed by the high d₀₀₁ spacing values (2.5 nm). Thermogravimetric analyses show a major weight loss between 230 °C and 500 °C corresponding to the release of organic matter. The mass spectrometry analyses of the evolved gas are in agreement with the presence of octyl chains. Infrared and ¹³C MAS NMR spectra indicate that the Si–C bonds are intact and that the siloxane functions are fully hydrolyzed giving Si–O–Al and Si–O–Mg bonds in the inorganic layers. The substitution of Si and Mg by Al was confirmed by ²⁹Si and ²⁷Al MAS NMR.