Material templating methods

Figure 74 The polyhexenyldecaborane (128) used in the production of nanostructured boron carbide materials by nanoscale templating methods utilizing porous alumina templates.

We chose to use a sacrificial template method to make our nanorods. This method uses a membrane with nano/microscopic sized channels as a mold for the design of a nanowire, fiber, or rod, depending upon the intended use for the object and the materials comprising it. ... 

The template method involves using the pores in a microporous solid as nanoscopic beakers for the synthesis of nanoparticles of the desired material [1,3,10]. A wide variety of materials are available for use as template materials [1,10,14-19]. Pore diameter sizes range from Angstroms to many p,m. Several of the more common materials used as templates are reviewed below. 

A variety of nanomaterials have been synthesized by many researchers using anodic aluminum oxide film as either a template or a host material e.g., magnetic recording media (13,14), optical devices (15-18), metal nanohole arrays (19), and nanotubes or nanofibers of polymer, metal and metal oxide (20-24). No one, however, had tried to use anodic aluminum oxide film to produce carbon nanotubes before Kyotani et al. (9,12), Parthasarathy et al. (10) and Che et al. (25) prepared carbon tubes by either the pyrolytic carbon deposition on the film or the carbonization of organic polymer in the pore of the film. The following section describes the details of the template method for carbon nanotube production. 

Encapsulation of other material into carbon nanotubes would also open up a possibility for the applications to electrodevices. By applying the template method, perfect encapsulation of other material into carbon nanotubes became possible. No foreign material was observed on the outer surface of carbon nanotubes. The metal-filled uniform carbon nanotubes thus prepared can be regarded as a novel onedimensional composite, which could have a variety of potential applications (e.g novel catalyst for Pt metal-filled nanotubes, and magnetic nanodevice for Fe304-filled nanotubes). Furthermore, the template method enables selective chemical modification of the inner surface of carbon nanotubes. With this technique, carbon... 

The template method will be able to produce various types of unique carbon nanotubes and one-dimensional carbon composites, and such unique materials would provide a variety of potential applications. 

Niobium and titanium incorporation in a molecular sieve can be achieved either by hydrothermal synthesis (direct synthesis) or by post-synthesis modification (secondary synthesis). The grafting method has shown promise for developing active oxidation catalyst in a simple and convenient way. Recently, the grafting of metallocene complexes onto mesoporous silica has been reported as alternate route to the synthesis of an active epoxidation catalyst [21]. Further the control of active sites, the specific removal of organic material (template or surfactant) occluded within mesoporous molecular sieves during synthesis can also be important and useful to develop an active epoxidation catalyst. Thermal method is quite often used to eliminate organic species from porous materials. However, several techniques such as supercritical fluid extraction (SFE) and plasma [22], ozone treatment [23], ion exchange [24-26] are also reported. 

The recent developments in science and technology require a more exact control of structure/ nanotexture and properties of various materials, including carbon materials. In order to meet the requirements for carbon materials, various novel carbonization processes have been proposed. In relation to electrochemistry, the following processes have to be mentioned template method, polymer blend method, defluorination of fluorinated hydrocarbons, and carbonization of organic aerogels [99],... 

The rhodium containing hybrid materials prepared with the BINOL bicarbamate moieties are less active and enantioselective than the previous hybrid catalyst. The observed enantioselectivity was attributed to supramolecular effect of the chiral tridimensional network owing to the weakness of the interaction of the transition metal and the chiral ligand. The control of the texture and morphology of these solids by templating methods firstly reported by Macquarrie39 and Mann40 with suitable surfactants would improve the catalytic performance of this new class of chiral materials. 

A templating method was presented to fabricate novel three-dimensional ordered macroporous silica materials ftinctionalized by polyoxometalates. Characterization of the products indicated that the starting XMo, remained intact regardless of the functionality of the polyanions, and their primary lacunry structures tended to get saturated. The future development of the method holds promise for the formation of advanced new materials with more novel properties, which can be applied in more wide fields. 

The template method is a general approach for preparing nanomaterials that entaU synthesis or deposition of the desired material within the cylindrical and monodisperse pores of a nanopore membrane or other solid [20-22]. Cylindrical nano-strucmres with monodisperse diameters and lengths are obtained, and depending on the membrane and synthetic method used, these may be solid nano wires or hollow nanombes. This method has been used to prepare nano wires and nanombes composed... 

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