Templating with Polymer and Surfactant Results

Residual organics and template materials, surfactants and polymers, can be removed simply by heating at temperatures up to 500°C. The heated gels at temperatures up to 600°C consist of anatase nanoparticles. Anatase titania is known to have higher photocatalytic activity than other crystalline phases of titania. At temperatures higher than 600°C, the phase 

Some examples of the pore properties for the dried and annealed gels are summarized in Table 7.1. 

Sample fiET surface area (m g ) Pore volume (cm g- ) Average pore diameter (run) 

The specific surface area of the surfactant- and polymer-templated gels, that is, the ambient pressure aerogels, is nearly the same as that of the aerogels prepared by the supercritical extraction of CO2. Also, the pore size and the pore volume, that is, the porosity, are larger (twice or more) than those of the xerogels, but smaller than those of the super-critically extracted aerogels, estimated to be ca. 55%. The pore size and pore volume depended on the properties of surfactants and polymers, molecular size, and micelle- or aggregate shape. Also, the concentration of polymers in the immersion solutions, as well as the kind of template materials, affected the pore size and pore volume (Table 7.2). 

Although the porosity and the pore size are smaller than those of the aerogels, the catalytic activity is improved. Some examples are shown in Table 7.3. 

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