Synthesis asymmetric nanosilica

Synthesis of Symmetric and Asymmetric Nanosilica for Materials, Optical and Medical Applications... 

The benefit of this division can be illustrated from several perspectives. From a synthetic point of view, the division is significant as synthesis normally results in the production of symmetric materials. Hence, the synthesis of asymmetric nanosilica and molecular species are quite unique by themselves. The division can thus be viewed as a helpful hint to understanding the synthesis of helical materials and other asymmetric nanomaterials. The origin of the production of asymmetric nanosilica is believed to be the nature of the different catalysts or templates involved, while the exact growth mechanism depends on the structure of these catalysts or templates. To date, asymmetric nanosihca has not been prepared without these two assisting species. 

The preparation of asymmetric nanosilica differs slightly from that of their symmetric counterparts, the main difference being an involvement of templates or anisotropic catalysts [28]. The addition of these materials initiates an asymmetric growth of nanomaterials, thus producing helical nano materials. In the template nanosiUca, a further treatment of as-made silica-like nanomaterials is required to convert them into real siUca nanomaterials. However, in the catalytic growth of heUcal nanomaterials such as nanocoils, no post-synthesis treatment is required. 

In this chapter we review the current state of research on symmetric and asymmetric silica nanomaterials, or nanosUica, in terms of their synthesis, characterizahon and applications. Both, catalyticaUy and noncatalytically grown nanosilica are discussed, and several types of application for these nanomaterials are described. For asymmetric nanosihca, the focus is on helical nanosilica such as silica nanocoils and other heh-cal nano silica, whereas for symmetric silica nanomaterials the discussion covers more general forms of nanosilica, including nanoparticles, mesoporous nanomaterials and sihca nanotubes. 

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