Interlayer Silylation of Layered Octosilicate with Organoalkoxysilanes: Effects of Tetrabutylammonium Fluoride as a Catalyst and the Functional Groups of Silanes

Interlayer silylation of layered sodium octosilicate (Na-Oct) with various organoalkoxysilanes was conducted using hexadecyltrimethylammonium ion-exchanged layered octosilicate (C(16)TMA-Oct) as an intermediate in the presence or absence of tetrabutylammonium fluoride (TBAF). The degree of silylation was increased by adding TBAF. It is suggested that F- ions perform a nucleophilic attack on the alkoxysilanes, which promotes the silylation reaction. C(16)TMA-Oct was silylated with octyltriethoxysilane (C8TES) or 3-mercaptopropyltriethoxysilane (MPTES) to compare the reactivity of the two organoalkoxysilanes in the presence or absence of TBAF. A higher degree of silylation of C(16)TMA-Oct was observed with MPTES, suggesting the higher accessibility of this silylating agent into the interlayer polar region of C(16)TMA-Oct. Overall TBAF appears as a relevant catalyst for the covalent interlayer surface modification of layered silicates with organic functional groups.

Automated summary

In this study, interlayer silylation of Na-Oct with various organoalkoxysilanes was conducted using C(16)TMA-Oct as an intermediate, with or without TBAF. The addition of TBAF increased the degree of silylation, possibly due to nucleophilic attack by F- ions. MPTES exhibited higher reactivity in silylation reactions, indicating better accessibility to the interlayer polar region of C(16)TMA-Oct.