Insights into grafting of (3-Mercaptopropyl) trimethoxy silane on halloysite nanotubes surface

Functionalization of halloysite nanotubes surface by using organosilanes is sensitive to the reaction conditions. Halloysite nanotubes (HNTs) were modified using (3-Mercaptopropyl) trimethoxy silane (MPTMS). The experiments were performed under different reaction conditions including, various solvents [Toluene, Tetrahydrofuran (THF), Ethanol, n-Hexane, 1,4 Dioxane and Acetonitrile], water content in the reaction media, volume of solvent, number of moles of silane and catalysts (triethyl amine, ammonia solution and tetra-ethoxy titanium). The elemental analysis, FT-IR analysis were used to identify the samples, which attained the highest percent of functionalization. SEM image and thermogravimetric analysis were provided for the pristine halloysite nanotubes and the modified halloysite nanotubes samples. This work provides a systematic investigation of the reaction conditions highlighting the best protocol to perform such a modification that represents a relevant strategy to control the surface properties of halloysite nanotubes as well as the optimization of the first step toward further modifications of this nano clay.