Spherical shapes mesoporous silica

However, the use of organogel superstructures for the creation of silica with novel morphologies is not only limited to fiber shaped structures. Due to their potential applications as adsorption media, molecular sieves and catalysts, the design of spherical mesoporous silica has been of special interest. Pioneering work in this area was done by Ozin et al with the synthesis of a lamellar alu-minophosphate phase in solution containing vesicles formed from tetraethylene... 

The materials which have been mentioned here so far are predominantly shaped in planar films of hierarchical order. However, the synthesis of hierarchically structured particles is also highly desirable, as they might be further processed and used for the preparation of composite porous materials. Wu et al. showed the synthesis of raspberry-like hollow silica spheres with a hierarchically structured, porous shell, using individual PS particles as sacrificial template [134]. In another intriguing approach by Li et al. [135], mesoporous cubes and near-spherical particles (Fig. 10) were formed by controlled disassembly of a hierarchically structured colloidal crystal, which itself was fabricated via PMMA latex and nonionic surfactant templating. The two different particle types concurrently generated by this method derive from the shape of the octahedral and tetrahedral voids, which are present in the template crystal with fee lattice symmetry. 

Macroporous silica possesses wide pores, whereas the pores of microporous silica are so small that the opposite sidewall of the pore will overlap due to the proximity of walls. The pores can be of different shapes such as spherical or cylindrical with varying arrangements. Some structures may have large pores (more than 50 nm) in one dimension, but the width of the same pore may be in mesorange, and hence material can be considered as mesoporous. Non-ordered MPS are characterized by randomly oriented, interconnected pores with a representative pores size distribution, whereas OMSs are characterized by ordered pore orientation and size. 

HMC is a very interesting porous carbon material with unique hierarchical macro/mesoporous spherical morphology. HMCs with various core sizes and/or shell thicknesses can be fabricated through the independent control of the core sizes and/or shell thicknesses of the SCMS silica templates [28,62,63], while the micro- and mesoporosity of the HMCs can be controlled to some extent by the source type and amount of carbon precursor incorporated into the SCMS silica template. HMC with different core shapes (non-spherical) have been synthesised through nanocasting techniques [61,64], A key factor for the s)mthesis of HMCs with diverse shapes and sizes lies in the fabrication of SCMS silica replica templates. 

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