Synthesis of phenyl-MSU-1 and bi-functionalized silica mesophases
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Feng Deng, Qing Luo, and Yong Yue State Key Laboratory of Magnetic Resonance and Atomic Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, 430071, People’s Republic of China (Received 24 August 2001; accepted 21 November 2001)
Template-directed co-condensation was used to synthesize phenyl-modified MSU-1 and bi-functionalized MSU-1 silica containing binary moieties of covalently linked phenyl along with methyl or ureidopropyl [H2NCONH(CH2)3]. The texture properties of these materials from x-ray diffraction, Fourier transform infrared, nuclear magnetic resonance, scanning electron microscopy, high-resolution transmission electron microscopy, N2 adsorption, thermogravimetric analysis data, varied with the type of alkoxylsilane precursor and the amount of organosiloxane in the mixture. Small-angle x-ray scattering results, for the as-synthesized and surfactant-extracted organo-modified MSU-X, showed that the templates remaining in the mesostructures gave positive deviation from Porod’s law while the incorporated organic groups led to a negative deviation, which formed an interfacial layer between the pore and silica matrix.
I. INTRODUCTION
Functionalized mesoporous silica materials have been demonstrated to be promising materials for several applications due to their inorganic “hard” framework and organic “soft” surface properties.1–11 The direct assembly of organosiloxane moieties in mesostructured silica has recently offered a greater synthetic ability than the grafting process, which can produce mesoporous solids with high loadings of the grafting process. The grafting process, in turn, can produce mesoporous solids with high loadings of organic functional groups and homogeneous surface coverage within a relatively short preparation time. 1–7 Various organic groups have been incorporated into MCM-41 silica frameworks by the cocondensation of siloxane and organosiloxane precursors under basic conditions (S+I− pathway)2–8 or under acid conditions (S+X−I+ pathway),9,10 but in some instances the functionalized mesostructure decomposes upon removal of the templating surfactant from the pores through acid leaching. These observations clearly illustrate a general disadvantage of electrostatic assembly for direct functionalization. In particular, the removal of the charged surfactant molecular from the framework by extraction techniques is problematic. a)
Address all correspondence to this author. e-mail: [email protected] J. Mater. Res., Vol. 17, No. 2, Feb 2002
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The neutral alternative pathways (S0I0/N0I0) were then developed for the organo-HMS and organo-MSU-X derivatives, respectively.1,11 In both cases, the surfactant molecules could be easily extracted from the mesostructures by ethanol extraction, resulting in hybrid organic–inorganic mesoporous frameworks. But most organo-HMS silica materials synthesized by Mercier and co-workers1 had small pore diameters (700 m2/g).
There was almost no variation in BET surfac
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