The Complete Control for the Nanosize of Spherical MCM-41

Abstract

In this work, we present a systematic study on the complete control over the sphere diameters of MCM-41 nanospheres with different pore sizes. The mesoporous silica nanospheres with diameter range from 40 nm to 160 nm are synthesized by using cationic quaternary ammonium surfactants as template and TEOS as silicon source in sodium hydroxide aqueous solution via sol-gel supermolecular method. Nanospheres with fixed diameter can be obtained through the precise control over the molar ratio of NaOH/TEOS and other synthetic conditions. The range of sphere diameter for each sample prepared under adjustable reaction conditions is in a sharp distribution. Moreover, the formation mechanism for nanospheres with controlled morphological and structural features is proposed, and we suggest the optimal synthesis conditions of the MCM-41 nanospheres for the minimization of the Gibbs free energy deltaG. Besides, after depositing vanadium species on the MCM-41 support, the catalytic performance of V-MCM-41 for the selective oxidation of styrene by hydroperoxide increases with the diameter of the supports decreasing.

Extracting Signatures of Spatial Organization for Biomolecular Nanostructures

“…[30][31][32][33][34][35][36][37][38] Elucidation of actual structural features of such small assemblies, especially smaller than 100 nm and more specifically in the sub-10 nm scales, has been possible (to some extent) by development of analytical tools for extracting geometrical signatures from indirect data measurements (e.g., molecular diffraction patterns 7 27 and application of techniques such as fluorescence resonance energy transfer 39 ). In general, pattern generation and recognition in 3-D space have been of wide interest in the area of molecular structures.…”

Colloidal and spherical mesoporous silica particles: synthesis and new technologies for delivery applications

“…Although many authors claimed to synthesize nanoparticles, only those showing proof of nanosized diameters [13,[15][16][17][18][19][20][21] are labeled as MSN (if no proof of crystal structure is shown by XRD). While some MCM-41 materials are listed [12,[22][23][24], only one was found for SBA-15 particles [24] in the submicron range, although resembling more an hexagonal shape, as it will be discussed later. Hiroshima Mesoporous Materials (HMM) [25] are another alternative where the polymerization of styrene is carried inside the surfactant micelles, and the hydrolyzed silica simultaneously condensates on the growing polystyrene chains inside the drops.…”

“…Thus, although MCM-41 has been the surfactant most studied so far, there are yet valuable reports addressing basic questions about the influence of synthesis conditions on the morphology of the final material, and more research is necessary to achieve the ideal of effectively controlling sizes and distributions of pores and particles. Aiming to this purpose, authors achieve nanoparticles sizes from 40 to 160 nm, with very narrow distributions and outstanding surfaces areas (up to 1208 m 2 /g), using quaternary ammonium surfactants [12]. The use of a longer carbon chain gives as a result an increase in pore size from 2.4 to 3.1 nm, but it is not affected neither by the temperature (20-80°C) nor by the stirring rate (200-700 rpm).…”

Facile and Rapid Synthesis of Pyrochlore W2O6·H2O Nanoplate via a Fluorinion-Assisted Hydrothermal Process

“…14 15 The innovative materials with outstanding performances and novel properties may be formed by the materials' nanoarchitectonics. [16][17][18] For example, Ariga and his co-workers developed a series of versatile technologies to construct layered and nanoporous functional materials. [19][20][21] These materials may * Author to whom correspondence should be addressed.…”