Synthesis of large-pore methylene-bridged periodic mesoporous organosilicas and its implications.
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.
Department of Chemical and Biomolecular Engineering, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119620.
Xiao Ying
XY
Bao
Xu
X
Li
X S
XS
Zhao
D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D046529:Microscopy, Electron, Transmission / Q000379:methods; D017646:Organosilicon Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D010316:Particle Size; D016062:Porosity; D053838:Scattering, Small Angle; D012680:Sensitivity and Specificity; D012822:Silicon Dioxide / Q000138:chemical synthesis* / Q000737:chemistry; D014961:X-Ray Diffraction
D017646:Organosilicon Compounds; C509969:SBA-15; D012822:Silicon Dioxide