Nanostructured, electroactive and bioapplicable materials

Chapter 1. An Overview to Nanostructured Porous Sol-Gel Materials
1.1. Introduction
The discovery in 1930s of the synthetic microporous zeolites, a series of
aluminosilicate materials with frameworks analogous to those formed geologically, has
brought up tremendous opportunities in many areas of advanced materials, from
fundamental scientific research to diverse industrial applications. 1-4 In the past few
decades, considerable efforts have been devoted to developing nanostructured (i.e.,
structures roughly in the 1-100 nm size range) porous materials with a wide range of
porosity, morphology and composition. The chemical and mechanical mechanisms that
influence porosity during and after the synthesis process have been extensively studied.
Advanced characterization methods and instruments have been developed, which greatly
facilitate the research in the field. With their unique structural properties, nanostructured
porous materials have been widely used as catalysts, 5,6 separation media, 7,8 sorption
materials, 9 ion-exchangers and bioreactors. 10
In the early 1990s, a surfactant templated synthetic route has been developed by
researchers at Mobil Corporations. 11,12 Known as M41S, silicon and other metal oxides
with periodic nanoporous structures have been obtained. While M41S has tunable pore
diameters of 1.5-10 nm, this was the first time that the pore size of synthetic porous
materials was expanded to the mesoscopic range. This breakthrough discovery created an
innovative strategy for the synthesis of nanostructured porous materials. Soon after, this
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