Microemulsion Templating of Siliceous Mesostructured Cellular Foams with Well-Defined Ultralarge Mesopores

Abstract

Siliceous mesostructured cellular foams (MCFs) with well-defined ultralarge mesopores and hydrothermally robust frameworks are described. The MCFs are templated by oil-inwater microemulsions and are characterized by small-angle X-ray scattering, nitrogen sorption, transmission electron microscopy, scanning electron microscopy, thermogravimetry, and differential thermal analysis. The MCFs consist of uniform spherical cells measuring 24-42 nm in diameter, possess BET surface areas up to 1000 m 2 /g and porosities of 80-84%, and give, because of their pores with small size distributions, higher-order scattering peaks even in the absence of long-range order. Windows with diameters of 9-22 nm and narrow size distribution interconnect the cells. The pore size can be controlled by adjusting the amount of the organic swelling agent that is added and by varying the aging temperature. Adding ammonium fluoride selectively enlarges the windows by 50-80%. In addition, the windows can be enlarged by postsynthesis treatment in hot water. The MCF materials resemble aerogels, but offer the benefits of a facilitated synthesis in combination with welldefined pore and wall structure, thick walls, and high hydrothermal stability. The open system of large pores give MCFs unique advantages as catalyst supports and separation media for processes involving large molecules, and the high porosities make them of interest for electrical and thermal insulation applications.

Expanding mesoporosity of triblock-copolymer-templated silica under weak synthesis acidity

“…1.7-2.0 cm 3 /g, which can be almost totally contributed by framework-confined porosity inferred from the nitrogen sorption analysis, and are significantly larger than that of MS cl À 0 (1.1 cm 3 /g). TMB has ever been used as swelling agent to create a largest pore volume of 2.2 cm 3 /g under strong acidities [4][5][6]. Thus the pore volumes of the mesoporous silica synthesized under mildly acidic conditions are rather high in comparison with the already reported data.…”

“…The big pore size and large pore volume is considered as desirable characteristic in the adsorption or catalysis applications especially when organics with bulky molecules are involved as adsorbates or reactants owing to facilitated mass transfer [3]. In recent years, much effort has been devoted to further expanding the porosity of SBA-15, and the general method was the utilization of swelling agents such as aromatics [1,[4][5][6] or alkanes [7][8][9][10], which could dissolve in the hydrophobic core of template micelles to make enlarged hydrophobic volume, leading to bigger pore size and larger pore volume. Large pore volume of up to 2.2 cm 3 /g was achieved with the use of mesitylene as swelling agent [1].…”

“…Large pore volume of up to 2.2 cm 3 /g was achieved with the use of mesitylene as swelling agent [1]. It was found that excess amounts of swelling agents in the synthesis mixture would lead to the change of structure from 2D hexagonal (SBA-15) to mesocellular foam (MCF) instead of further increasing the diameter of mesochannels [4][5][6]. Up to now, organic swelling agents are generally required in order to obtain mesoporous silicas with large pore volume of more than 1.3 cm 3 /g in most cases.…”

Alcohol Oxidation at Platinum–Gas and Platinum–Liquid Interfaces: The Effect of Platinum Nanoparticle Size, Water Coadsorption, and Alcohol Concentration

“…In order to study the catalytic alcohol oxidation reaction with molecular oxygen in the gas and liquid phases, we chose the mesoporous silica MCF-17 as the Pt support. 15,16 MCF-17 has wide pore size ranges from 15 to 50 nm which are adequate to incorporate the sub 10 nm Pt NPs. The amount of Pt loaded into the supports was measured by inductively coupled plasma atomic emission spectroscopy (ICP-AES).…”

Síntese e caracterização de beads acrílicos preparados por polimerização em suspensão visando aplicação como excipiente farmacêutico para compressão direta

“…A MCM-41 possui arranjo hexagonal de mesoporos e sistemas de poros unidimensionais. 58,59 O trabalho foi dividido em três etapas. Na primeira, foram preparados beads por meio de polimerização em suspensão, empregando CNW e MCM-41 como estabilizantes, visando a obtenção de excipientes para a preparação de comprimidos matriciais de liberação prolongada.…”