Templating method replica surfaces

Figure 1 Typical superhydrophobic surface structure fabricated by templating method (A) replica of Co/ocas/a-like leaf surface on PDMS template (Singh et al., 2007), (B) a microporous pattern of polyvinylidene fluoride film (Li et al., 2006), (C) superhydrophobic hair shaped polymer surface grown through an AAO template (Zhang et al., 2006) and (D) water droplet resting on a polymer hot-press transferred pattern (Bormashenko et al., 2006). PDMS, polydimethylsiloxane AAO, aluminum oxide. Images reprinted with permission from (A, B) Elsevier, Copyright2007and2006 respectively, (C, D) American Chemical Society, Copyright2006.

Unlike CMK-1 [62], here the ordered pore structure (see Figure 2.15b) is a true replica of SBA-15, without involving strnctural transformation that occurs when MCM-48 is nsed as a template [62,121], The overall porosity of CMK-3 is a combination of nniform pores in spaces between the ordered carbon nanorods and micropores within these nanorods. The carbon is mostly mesoporous, with a quite narrow PSD centered at about 4.5 nm, as calculated using the Barrett-Joyner-Halenda (BJH) method [120]. The carbon nanorods in CMK-3 are about 7 nm in diameter, and the centers of two adjacent rods are about 10 nm apart, whereas the surface-to-surface distance is about 3 nm, based on XRD and TEM results [120]. The carbon nanorods are interconnected by carbon spacers [122], as illustrated in Figure 2.14. Because the pore size of SBA-15 can be tuned simply by changing the synthesis conditions, the mesopore size of templated carbon can be tuned in the 3.0- to 5.2-nm range [123]. 

The formation of open and porous structures with extremely large surface area is of high technological significance, because this structure type is very suitable for electrodes in many electrochemical devices, such as fuel cells, batteries and sensors [1,2], and in catalysis applications [3]. The template-directed synthesis method is most commonly used for the preparation of such electrodes. This method is based on a deposition of desired materials in interstitial spaces of disposable hard template. When interstitial spaces of template are filled by deposited material, the template is removed by combustion or etching, and then the deposited material with the replica structure of the template is obtained [4, 5]. The most often used hard templates are porous polycarbonate membranes [6, 7], anodic alumina membrane [8-10], colloidal crystals [11, 12], echinoid skeletal stractures [13], and polystyrene spheres [14, 15]. 

Sol-gel method (Zhang, 2002), replica process (Imai, 1999), and template approach (Kobayashi, 2000) have been reported as the procedures for the preparation of Ti02 nanotubes, and hollow tubes in the diameter of over 100 nm have been prepared. In practice, these materials have not been successfully commercialized as photocatalyst probably due to difficulties of its durability, costs, etc, however morphological approach may be effective in future application to air and water purification in light of its large surface area and unique structure like zeolite. 

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