Hollow core-shell mesoporous silica

The sphere synthesis has been extended into other materials. For example, mesoporous carbon capsules[285] with hollow core and mesoporous shell structures were synthesized using submicrometer-sized solid core and mesoporous-shell silica spheres as templates. 

Because of the uniquely ordered structure of template-synthesized porous carbons, they themselves can be used as templates to replicate other materials with an ordered porous structure that is difficult to make using traditional methods [121,338-348], Thus, CMK-3 carbon was first demonstrated as a template to prepare mesoporous silica [121,338]. An OMC prepared from an MCM-48 template was used to prepare nanostructured silica [339]. Nanocasting of CMK-3 using ZSM-5 crystals yielded a mesoporous zeolite with both mesopores and micropores [340]. More recently, the preparation of a novel class of mesoporous aluminosilicate molecular sieves was described [341]. The preparation of mesoporous boron nitride (MBN) and mesoporous carbon nitride (MBCN) with very high surface area and pore volume was recently realized using a well-ordered hexagonal mesoporous carbon as a template and boron trioxide as a boron source [342]. Nonspherical silica nanocases with a hollow core and mesoporous shell were also produced [343]. 

Zhu Y, Shah NH et al (2002) Influence of thermal processing on the properties of chlorpheniramine maleate tablets containing an acrylic polymer. Phaim Dev Technol 7(4) 481-489 ZhuY, Shi J et al (2005) Stimuli-responsive controlled dmg release from a hollow mesoporous silica sphere/polyelectrolyte multilayer core-shell structure. Angew Chem Int Ed 44 5083-5087 Zhu Y, Shah NH et al (2006) Controlled release of a poorly water-soluble drug from hot-melt extrudates containing acrylic polymers. Drug Dev Ind Pharm 32 569-583... 

Fig. 18 TEM images (a, b) of hollow mesoporous silica sphere (HMS) with a 3D pore network, core-shell structure, (c) with polyelectrolyte multilayer coating as a stimuli-responsive...

Y.F. Zhu, J.L. Shi, W.H. Shen, X.P. Dong, J.W. Feng, M.L. Ruan, and Y.S. Li, Stimuli-Responsive Controlled Drug Release from a Hollow Mesoporous Silica Sphere/Polyeleclrolyte Multilayer Core-Shell Structure, Angew. Chem. Ini. Ed., 44, 5083-5087(2005). 

J., Ruan, M., and Li, Y. (2005) Stimuli-responsive controlled drug release from a hollow mesoporous silica sphere/ polyelectrolyte multilayer core-shell structure. Angew. Chem., Int. Ed., 44, 5083-5087. 

The first HMC with spherical macroporous core was developed by our research group using submicrometre-size spherical solid core-mesoporous shell (SCMS) silica as the template [60]. Discussed below are surface structural features such as the sizes of hollow core and of mesopores in the shell, the thickness of the mesoporous shell and other highly dependent parameters. Specific surface area and pore volume play a pivotal role in determining physiochemical, electrochemical and photochemical properties of the HMC materials. The HMC capsules are expected to demonstrate considerably improved performance in energy applications such as rechargeable ElBs, ECs and fuel cells, owing to their unique structural characteristics. 

Mesosize- and microsize-thick silica walls can be formed in the shell of the SCMS silica from the interaction of Cjg-TMS and TEOS, which are the primary sources of meso- and micropores of the replicated HMC. In general, the higher ratio of C g-TMS to TEOS tends to increase the size of the meso-pore and decrease the silica wall thickness in the shell of the SCMS silica, thus to some extent increasing the micropore volume in the corresponding HMC [28,62]. A carbon precursor can be incorporated into the mesoporous channels separated by silica walls in the shell of the SCMS silica, and after carbonisation of the polymerised carbon precursor and removal of SCMS silica, HMCs with macroporous hollow core in combination with meso/ microporous shell can be produced (with various surface area, pore volume and meso- and microporosity) (see Figure 4.1). 

J.-S. Yu, S.-B. Yoon, Y.-J. Lee and K.-B. Yoon, Fabrication of bimodal jxjrous silicate with silicalite-1 core/mesoporous shell structures and synthesis of non spherical carbon and silica nano cases with hollow core/mesoporous shell structures, /. Phys. Chem. B 109,2005, 7040-7045. 

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