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Abstract:
Solvent-free synthetic approaches are very attractive to curtail the chemical waste generation and simplify processes. Mechanochemistry has recently shown great potential in this direction. Here, we demonstrate the mechanochemical grafting for the synthesis of hybrid inorganic–organic materials in 5 min at room temperature without the use of any solvent. The mechanochemical functionalization of different solids (SBA-15, γ-Al2O3, SiO2 gel, and TiO2) with various organosilicon compounds (alkyltrialkoxysilanes or trialkylmonohalosilane) is confirmed by characterizing the resulting composite in detail by thermogravimetric analysis coupled to mass spectrometry, 29Si magic angle spinning nuclear magnetic resonance spectroscopy, and Fourier transform infrared spectroscopy, which suggest the formation of chemical bonds between the solid surfaces and silanes. X-ray diffraction analysis shows that the original ordered mesoporous character of SBA-15 and crystalline structures of γ-Al2O3 or TiO2 are retained after grafting. N2 sorption evidences a decrease in specific surface areas, pore diameters, and pore volumes due to the silane functionalization. Our results show that the mechanochemical silylation is efficient and likely involves the direct condensation between alkoxy or halo groups of silane and surface hydroxyls of the solids. These results, providing a general, simple, highly efficient, and solvent-free alternative to solvothermal routes for the fabrication of hybrid materials, might lead to a new pathway for the preparation of different composites for various technological applications.
