Synthesis, Characterization and Use of Mesoporous Silicas of the Following Types SBA-1, SBA-2, HMM-1 and HMM-2

Abstract

Mesoporous silicas have enjoyed great interest among scientists practically from the moment of their discovery thanks to their unique attractive properties. Many types of mesoporous silicas have been described in literature, the most thoroughly MCM-41 and SBA-15 ones. The focus of this review are the methods of syntheses, characterization and use of mesoporous silicas from SBA (Santa Barbara Amorphous) and HMM (Hybrid Mesoporous Materials) groups. The first group is represented by (i) SBA-1 of three-dimensional cubic structure and Pm3n symmetry and (ii) SBA-2 of three-dimensional combined hexagonal and cubic structures and P63/mmc symmetry. The HMM group is represented by (i) HMM-1 of two-dimensional hexagonal structure and p6mm symmetry and (ii) HMM-2 of three-dimensional structure and P63/mmc symmetry. The paper provides comprehensive information on the above-mentioned silica materials available so far, also including the data for the silicas modified with metal ions or/and organic functional groups and examples of the materials applications.

High Surface Area Mesoporous Silica Nanoparticles with Tunable Size in the Sub-Micrometer Regime: Insights on the Size and Porosity Control Mechanisms

“…A basic, aqueous, 5 mM CTAB solution, which is above the critical micellar concentration, and characterized by hexagonal structures, has been heated up at T injection and ethanol and TEOS have been added, under stirring, resulting in a homogenous colloidal solution (Figure 1A, Step 1(i)). According to the commonly reported procedures (see reactions (1) and (2) below), the basic pH provided by NaOH promotes the hydrolysis of TEOS, bursting the nucleation of the MSNs and supporting the further condensation of Si-O-Si networks, while the presence of CTAB micelles, interacting with the silica precursor, templates mesopores formation. The obtained MSNs have been aged at room temperature (Figure 1A, Step 1(ii)) for a defined time (t ageing ), under stirring, prior their separation from the reaction mixture by centrifugation.…”

“…Silica-based mesoporous nanoparticles (MSNs) have attracted increasing attention as nanocontainers [1][2][3] thanks to their high specific surface area, easy and versatile surface chemistry modification [4], narrow pore size distribution, tunable characteristics of pore network, with pore size ranging from 2 to 50 nm, and excellent biocompatibility with use of triethanolamine (TEA) for synthesizing MSNs with diameter ranging between 20 and 150 nm has been widely reported [27]. It sets reaction mixture pH at 9-10, required for the hydrolysis of alkoxides precursors and growth of porous structures, meanwhile its chelating behavior limits the MSNs growth [27].…”

“…Silica-based mesoporous nanoparticles (MSNs) have attracted increasing attention as nanocontainers [ 1 , 2 , 3 ] thanks to their high specific surface area, easy and versatile surface chemistry modification [ 4 ], narrow pore size distribution, tunable characteristics of pore network, with pore size ranging from 2 to 50 nm, and excellent biocompatibility with minimal non-specific or adverse effects [ 5 , 6 ]. These features make these structures potential candidates for delivery of active payloads useful in several fields of application [ 7 ] including catalysis [ 8 ], separation [ 9 ], energy storage [ 10 ], corrosion protection [ 11 ] and in biomedicine [ 12 ], as drug reservoir and bioimaging platforms.…”

“…Most of the synthetic approaches used to prepare MSNs derive from the pioneering work of Stöber [ 13 ], based on a sol-gel process of an alkoxysilane in water-alcohol solution, at ambient conditions in the presence of ammonia, as base catalyst, and modified via addition of a pore-structuring agents. In general, alkaline, as well as acidic, conditions [ 1 ] have been exploited to catalyze hydrolysis and condensation of a silica precursor that self-assembles with the organic structure directing agents (SDA), i.e., surfactants, co-surfactants and swelling agents. Therefore, formation of the MSNs results from a judicious combination of templating methods and inorganic sol-gel procedures.…”

Stress-Dependent Particle Interactions of Magnesium Aluminometasilicates as Their Performance Factor in Powder Flow and Compaction Applications

“…A variety of silicate materials has been explored. In addition to the application in the pharmaceutical industry discussed below, silicates are widely used in a number of other branches of science and industry, such as adsorption of hazardous pollutants, catalysis, enzyme immobilization, optics industry, and others [ 1 , 2 , 3 , 4 , 5 , 6 ].…”