Synthesis of an Alkylammonium/Magnesium Phyllosilicate Hybrid Nanocomposite Consisting of a Smectite-Like Layer and Organosiloxane Layers

We synthesized a novel alkylammonium/magnesium phyllosilicate hybrid compound by hydrothermal reaction from a mixture of octadecyldimethyl(3-trimethoxysilylpropyl)ammonium chloride, silica sol, and Mg(OH) 2 . The structure of the hybrid compound was studied by XRD, TEM, electron diffraction, high-resolution solid-state NMR, TG-DTA/MS, and elemental analysis. The oscillating XRD profile indicated that the compound has a layered structure without long-range periodicity, i.e., the synthesized platelet crystal is very thin. We proposed that the compound consists of three layers, in which the central layer is a magnesium phyllosilicate analogous to trioctahedral smectites, and the sheets on both sides are siloxanes. An organic part (C 18 H 37 N + (CH 3 ) 2 C 3 H 6 −) bonds to the layers and exists between them; the hybrid compound is an assembly of a magnesium phyllo(alkylammonium)silicate part and two condensed octadecyldimethyl(3-trimethoxysilylpropyl)ammonium chloride parts; the alkylammonium chains of both parts are in an all-trans conformation and are arranged in parallel.