Morphologies of mesoporous silicas

Single Crystal and Morphologies of Mesoporous Silicas Single Crystal ... 

Poyraz, A.S. and Dag, O. (2009) Role of organic and inorganic additives on the assembly of CTAB-P123 and the morphology of mesoporous silica particles./. Phys. Chem C, 113 (43), 18596-18607. 

SEM micrographs of the mesoporous materials prepared from C 6TMAB-HN03-TE0S-H20 composition, with and without the addition of PEO-6000 polymer, are shown in Fig. 1. In the absence of this polymer additive, mesoporous silica with gyroidal particulate morphology (Fig. 1 A) was formed even under the shear flow conditions. On the other hand, the addition of this polymer promotes the formation of mesoporous silica materials with millimeter-sized, rope-... 

To improve the meso-structural order and stability of the mesoporous silica ropes, a postsynthesis ammonia hydrothermal treatment (at 100 °C) was invoked. As indicated by the XRD profile in Fig. 3A, 4-5, sharp features are readily observed in ammonia hydrothermal treated samples. Moreover, after the post-synthesis ammonia treatment, the sample also possesses a sharp capillary condensation at p/po 0.35(Fig. 3B) corresponding to a much narrower BJH pore size distribution of ca. 0.12 nm (at FWHM). In other words, the mesostructures are not only more uniform but also more stable when subjected to the post-synthesis treatment. The morphology of the silica ropes remained unchanged during the ammonia hydrothermal process. The mesostructures remain intact under hydrothermal at 100 °C in water even for extended reaction time (> 12 h). 

In this paper, we report the synthesis of mesoporous silica and alumina spheres with nanometer size (80 to 900 nm) in the present of organic solvent with aqueous ammonia as the morphological catalyst to control the hydrolysis of tetraethyl orthosilicate (TEOS) and aluminum tri-sec-butoxide.1181 Mesoporous silica spheres show hexagonal arranged pores with monodispersed pore sizes ( 2.4 nm) and high surface areas ( 1020 m2/g) similar to MCM-41. A large pore ( 10 nm) mesoporous alumina sphere templated by triblock copolymer is thermally stable. Calcined alumina sphere shows disordered mesoporous arrays with relatively uniformed pore size distribution and high surface areas ( 360 m2/g). 

Figure 16.3 Some morphologies and sizes of mesoporous silica particles (a) to (c) spherical with different sizes and textures (d) to (f) rod-like with different sizes.

Figure 2.4. Scanning electron microscopy images of mesoporous silica synthetic morphologies (a) low- and high-curvature morphologies, (b) hollow helicoidal morphologies. Reproduced with permission from [41] and [47],...

We used both of mesoporous silica so called FSM and MCM-41, and mesoporous silica of a spherical morphology (GB). FSM samples were prepared by Toyota s group, while MCM-41 and GB were prepared by the group of Johannes Gutenberg University. In this article, FSM and GB samples of the different porosity are denoted by the number like FSMl. Their porosities are shown in Table 1. The pore width of used samples is in the range of 2.5 to 4.6 nm. The detailed preparation conditions and pore structures were published on previous joumals[25.26]. 

S.N. Che, Y. Sakamoto, O. Terasaki, and T. Tatsumi, The Structure and Morphology Control of Mesoporous Silica under Acidic Conditions, Microporous Mesoporous Mater., 2005, 85, 207-218. 

Typically, SEM is used to determine the continuity and the thickness of the film. Large-scale cracks and defects of the film can be determined by top view SEM images, and film thickness is easily obtained from cross-sections. It has been used extensively with powdered samples of mesoporous silica to determine morphology and thus assist in phase determination. However, thin films produced by dip and spin coating typically have a scarcity of features that may be resolved in SEM. This can be seen in Figs. 6A and 6B, SEM images of a mesoporous films templated with P123. 

The cellular uptake efficiency and kinetics together with the correlation between the particle morphology and aggregation of two kind, spherical and tubeshaped particles, of mesoporous silica nanomaterials (MSNs) were investigated... 

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