Synthesis of Large-Pore Methylene-Bridged Periodic Mesoporous Organosilicas and Its Implications

• Published in: The journal of physical chemistry. B Vol. 110; no. 6; pp. 2656 - 2661
• Main Authors: Bao, Xiao Ying, Li, Xu, Zhao, X. S
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 16.02.2006
• Subjects: Magnetic Resonance Spectroscopy - methods; Microscopy, Electron, Transmission - methods; Organosilicon Compounds - chemical synthesis; Organosilicon Compounds - chemistry; Particle Size; Porosity; Scattering, Small Angle; Sensitivity and Specificity; Silicon Dioxide - chemical synthesis; Silicon Dioxide - chemistry; X-Ray Diffraction
• DOI: 10.1021/jp0561120
• ISSN: 1520-6106

In this article, we report the synthesis of methylene-bridged periodic mesoporous organosilicas (PMOs) of the SBA-15 type. The materials were characterized by SAXS, BET, NMR, FESEM, and TEM. It was found that the synthesis of methylene-bridged SBA-15 PMOs requires more rigorous conditions than that of SBA-15 PMOs bearing organic bridges other than methylene. A mild acidic environment, which slows down the hydrolysis and condensation rates of the precursor, with the assistance of a salt, which enhances precursor−template interaction, should be used to synthesize high-quality large-pore methylene-bridged PMOs. We attributed this to the fast hydrolysis and condensation rates and the rigid backbone of precursor 1,2-bis(triethoxysilyl)methylene. By examining and comparing the synthesis of three large-pore PMOs with different bridges, we concluded that the inductive, bridging, and conformation effects of the organic bridging group play an important role in the synthesis of large-pore PMO materials.