Efficient Way to Attach Organosilyl Groups in the Interlayer Space of Layered Solids

An efficient method to immobilize silane-coupling reagents on the interlayer space of a layered silicate, magadiite (Na2Si14O29·nH2O), is reported. The silylation was conducted by concentrating a mixture containing the pre-synthesized dodecyltrimethylammonium-exchanged magadiite and a stoichiometric amount (molar ratio of silane-coupling reagent/Si14O29 unit of magadiite = 2.0) of (3-mercaptopropyl)trimethoxysilane. The resulting silylated derivative possessed basal spacing and had a composition comparable to those of the silylated derivative, prepared by using a previous silylation method, which involves dodecyltrimethylammonium-exchanged form with a much larger amount (molar ratio of silane-coupling reagent/Si14O29 unit of magadiite = 57) of the silane-coupling reagent. When the present method was employed, the surface coverage with (3-mercaptopropyl)silyl groups on the layer surface directly correlated to the amount of the silane-coupling reagent.