Synthesis and Characterization of Functionalized Mesoporous Silica by Aerosol-Assisted Self-Assembly

Abstract

An efficient, productive, and low-cost aerosol-assisted self-assembly process has been developed to produce organically modified mesoporous silica particles via a direct co-condensation of silicate species and organosilicates that contain nonhydrolyzable functional groups in the presence of templating surfactant molecules. Different surfactants including cetyltrimethylammonium bromide, nonionic surfactant Brij-56, and triblock copolymer P123 have been used as the structure-directing agents. The organosilanes used in this study include tridecafluoro-1,1,2,2-tetrahydrooctyltriethoxysilane, methytriethoxysilane, vinyltrimethoxysilane, and 3-(trimethoxysilyl)propyl methacrylate. X-ray diffraction and transmission electron microscopy studies indicate the formation of particles with various mesostructures. Fourier transform infrared and solid-state nuclear magnetic resonance spectra confirm the organic ligands are covalently bound to the surface of the silica framework. The porosity, pore size, and surface area of the particles were characterized using nitrogen adsorption and desorption measurements. This method provides a direct synthesis route to efficiently synthesize a large variety of organic functionalized mesoporous silica particles with controlled pore sizes, pore surface chemistry, and pore structures for catalyst, filler, and other applications.

Aerosol-assisted synthesis of mesoporous organosilica microspheres with controlled organic contents

“…The 29 Si MAS NMR spectra of Samples 1, 2 and 3 are shown in figure 6(a). For Sample 1, three peaks were observed at −109.7 (Q 4 , (SiO) 4 Si), −100.9 (Q 3 , (SiO) 3 SiOH) and −91.2 (Q 2 , (SiO) 2 Si(OH) 2 ) ppm.…”

“…After purging with N 2 for 1 h, thermogravimetry (TG) analysis was performed in an air flow with an SII EXTAR TG/DTA 6200 setup at a heating rate of 2 • C min −1 . Solid-state 29 Si magic angle spinning (MAS) nuclear magnetic resonance (NMR) measurements were performed with a Varian VNMR6.1C (300 MHz) spectrometer at a spinning rate of 5 kHz and a resonance frequency of 59.59 MHz with a 90 • pulse length of 3.6 µs and a recycle time of 100 s. Solid-state 13 C CP/MAS NMR measurements were performed on the same apparatus using a cross-polarization (CP) technique (spinning rate: 4 kHz; resonance frequency: 75.43 MHz; recycle time: 5 s). Samples were preheated at 110 • C for 6 h under vacuum, and then, the water adsorption-desorption isotherm was measured with a BELSORP 18 (Bel Japan Inc.) setup at 25 • C.…”

“…silica [23][24][25][26][27], organosilica [28][29][30], maghemite-organosilica [31], carbon [32] and metal oxide [33]) have been prepared by spray drying (i.e. aerosol-assisted process) [34].…”

“…clear precursor solution) is sprayed through a nozzle into a hot steam gas, in which the supplied liquid is vaporized and droplets are dried immediately. The system used previously is not suitable for the continuous production of solids, because dried samples are collected using membrane filters [23][24][25][26][27][28][29][30][31][32][33][34]. Recently, we developed a laboratory-made apparatus suitable for rapid mass production and industrial uses [35][36][37][38][39].…”

“…We demonstrated the facile preparation of PMO with different organic contents in the frameworks by changing the BTSE/TEOS molar ratios of initial precursor solutions. To the best our knowledge, a systematical study focusing on the control of organic contents has not been reported thus far, though several spray-dried mesoporous materials with different compositions have been designed by adjusting the composition of precursor solutions [23][24][25][26][27][28][29][30][31][32][33][34]. We demonstrated here that ethane and benzene fragments were successfully embedded in the frameworks (up to a BTSE/TEOS molar ratio of 0.50) with the formation of ordered mesoporous structures.…”