Organically modified MSU- x mesophases containing phenyl, ureidopropyl and methyl along with phenyl two moieties were directly prepared by one- pot synthesis method. Their texture and surface properties were character...Organically modified MSU- x mesophases containing phenyl, ureidopropyl and methyl along with phenyl two moieties were directly prepared by one- pot synthesis method. Their texture and surface properties were characterized by means of XRD, HRTEM, FT- IR, N2 adsorption/desorption, 29Si CPMAS NMR、 13C CPMAS NMR and the microscopic structure was also characterized by small angle X- ray scattering (SAXS) using synchrotron radiation as X- ray source. The results showed that SAXS profiles were hardly constant with Porod′ s law showing a negative slope, i.e. negative deviations (see fig.3). This suggested that the organic groups covalently linked with the matrix of mesoporous silica formed an interfacial layers, which led to the scattering of the pore distortion and gave a negative diviation from Porod′ s law. The average thickness of the interfacial layer in each sample was further obtained by analyzing this deviation. SAXS analysis also showed that the organically functionalized MSU- X displayed mass fractal and the uniform distribution of the organic groups within the mesoporous channels, implying that it′ s formation was a non- equilibrium and non- linear process.展开更多
Non-ionically templated organo-modified MSU-2 mesoporous silicas have been prepared in neutral medium by co-condensation TEOS and vinyltriexoylsiloxane (VTES) and exhibit highly symmetric bimodal mesopore systems. A b...Non-ionically templated organo-modified MSU-2 mesoporous silicas have been prepared in neutral medium by co-condensation TEOS and vinyltriexoylsiloxane (VTES) and exhibit highly symmetric bimodal mesopore systems. A bromination reaction of V-MSU-2 provides evidence for attachment of most vinyl groups to the accessible surface within the channels. Further, siliceous MSU-2 materials with double pore size have been obtained from calcination of so-produced organo-modified MSU-2 and demonstrate the immense flexibility of the non-ionic templating system.展开更多
The synthesis of silica with bimodal, disordered mesopores structure, by template-mediated sol-gel processing and subsequent heat-treatment process, was investigated. In the presence of nonionic surfactant Tx-15, the ...The synthesis of silica with bimodal, disordered mesopores structure, by template-mediated sol-gel processing and subsequent heat-treatment process, was investigated. In the presence of nonionic surfactant Tx-15, the organically modified mesostructured nano-particles were synthesized by co-condensation of organosiloxane （RTES） and tetraethoxysilane （TEOS） in the first step, and then the bimodal porous silica was formed by the removal of the incorporated organic groups using programmed calcination. Here, RTES used was methyltriethoxysilane （MTES）, vinyltriethoxysilane （VTES） and phenyltriethoxysilane （PhTES）, respectively. Organotrialkoxysilane, TEOS and Tx-15 formed MSU-2-1iked assemblies, around which the nano-particles aggregated and cross-linked, considerably influencing the pore size distribution of both primary pores and secondary pores. By changing the type and amount of the organotrialkoxysilane added, a broad variety of silica with a controlled bimodal mesopore distribution could be easily synthesized. Textural and structural properties were determined by X-ray diffraction, high-resolution transmission electron microscopy, N2 adsorption/desorption, and thermogravimetric analysis.展开更多
文摘Organically modified MSU- x mesophases containing phenyl, ureidopropyl and methyl along with phenyl two moieties were directly prepared by one- pot synthesis method. Their texture and surface properties were characterized by means of XRD, HRTEM, FT- IR, N2 adsorption/desorption, 29Si CPMAS NMR、 13C CPMAS NMR and the microscopic structure was also characterized by small angle X- ray scattering (SAXS) using synchrotron radiation as X- ray source. The results showed that SAXS profiles were hardly constant with Porod′ s law showing a negative slope, i.e. negative deviations (see fig.3). This suggested that the organic groups covalently linked with the matrix of mesoporous silica formed an interfacial layers, which led to the scattering of the pore distortion and gave a negative diviation from Porod′ s law. The average thickness of the interfacial layer in each sample was further obtained by analyzing this deviation. SAXS analysis also showed that the organically functionalized MSU- X displayed mass fractal and the uniform distribution of the organic groups within the mesoporous channels, implying that it′ s formation was a non- equilibrium and non- linear process.
文摘Non-ionically templated organo-modified MSU-2 mesoporous silicas have been prepared in neutral medium by co-condensation TEOS and vinyltriexoylsiloxane (VTES) and exhibit highly symmetric bimodal mesopore systems. A bromination reaction of V-MSU-2 provides evidence for attachment of most vinyl groups to the accessible surface within the channels. Further, siliceous MSU-2 materials with double pore size have been obtained from calcination of so-produced organo-modified MSU-2 and demonstrate the immense flexibility of the non-ionic templating system.
文摘The synthesis of silica with bimodal, disordered mesopores structure, by template-mediated sol-gel processing and subsequent heat-treatment process, was investigated. In the presence of nonionic surfactant Tx-15, the organically modified mesostructured nano-particles were synthesized by co-condensation of organosiloxane （RTES） and tetraethoxysilane （TEOS） in the first step, and then the bimodal porous silica was formed by the removal of the incorporated organic groups using programmed calcination. Here, RTES used was methyltriethoxysilane （MTES）, vinyltriethoxysilane （VTES） and phenyltriethoxysilane （PhTES）, respectively. Organotrialkoxysilane, TEOS and Tx-15 formed MSU-2-1iked assemblies, around which the nano-particles aggregated and cross-linked, considerably influencing the pore size distribution of both primary pores and secondary pores. By changing the type and amount of the organotrialkoxysilane added, a broad variety of silica with a controlled bimodal mesopore distribution could be easily synthesized. Textural and structural properties were determined by X-ray diffraction, high-resolution transmission electron microscopy, N2 adsorption/desorption, and thermogravimetric analysis.
