Examples of Functional Materials

Examples of Functional Materials with Different Defect Structures 69 When both contributions are significant... 

Examples of Functional Materials u/ith Different Defect Structures 71... 

Examples of Functional Materials ivith Different D ffect Structures 73... 

In this review, the potential uses of sonochemistry for the preparation of monometallic and bimetallic metal nanoparticles and metal-loaded semiconductor nanoparticles have been highlighted. While specific examples available in the literature were discussed, the sonochemical technique seems to offer a platform technique that could be used for synthesizing a variety of functional materials. Most of the studies to date deal with laboratory scale exploration , it would be ideal if the concepts are tested under large scale experimental conditions involving specific applications. The authors sincerely hope that the information provided in this review would prompt such experimental investigation in a new dimension. 

Sol-gel processing forms the basis for various routes employed for the fabrication of a wide diversity of functional materials. To impart a structural organization at various length scales, the syntheses are performed using templates. Most consist of a self-organized ensemble of surfactants and co-polymers [1-10]. They have been successfully applied to control the geometry and dimensions of pores that are periodically arranged as in the initial structures. Mesoporous silica materials of the MCM family, which were first synthesized by a team from the Mobil oil company [11,12], are a well-known example. 

An example of a material (Li3Sb) with a very large Wagner factor is shown in Fig. 8.3. The effective chemical diffusion coefficient is compared with the diffusivity as a function of non-stoichiometry. These data were determined by electrochemical techniques (see Section 8.5). An increase of the diffusion coefficient is observed at about the ideal stoichiometry which corresponds to a change in the mechanism from a predominantly vacancy to interstitial mechanism. The Wagner factor W is as large as 70 000 at the ideal stoichiometry. This gives an effective diffusion coefficient which is more typical of liquids than solids. It is a common... 

Synthesis of aminopolysaccharides, therefore, is one of the important research areas in the field of functional materials, examples of biorelated polymers, antibacterial substance, and biodegradable polymers as well as materials for drugs and matrices of drug delivery systems. Only a few methods, however, such as ring-opening polymerization and enzymatic polymerization have been available for the precision synthesis of aminopolysaccharides [4,5],... 

By covalent linkage of different types of molecules it is possible to obtain materials with novel properties that are different from those of the parent compounds. Examples of such materials are block-copolymers, soaps, or lipids which can self-assemble into periodic geometries with long-range order. Due to their amphiphilic character, these molecules tend to micellize and to phase-separate on the nanometer scale. By this self-assembly process the fabrication of new na-noscopic devices is possible, such as the micellization of diblock-co-polymers for the organization of nanometer-sized particles of metals or semiconductors [72 - 74]. The micelle formation is a dynamic process, which depends on a number of factors like solvent, temperature, and concentration. Synthesis of micelles which are independent of all of these factors via appropriately functionalized dendrimers which form unimolecular micelles is a straightforward strategy. In... 

Monodisperse spherical colloids and most of the applications derived from these materials are still in an early stage of technical development. Many issues still need to be addressed before these materials can reach their potential in industrial applications. For example, the diversity of materials must be greatly expanded to include every major class of functional materials. At the moment, only silica and a few organic polymers (e.g., polystyrene and polymethylmethacrylate) can be prepared as truly monodispersed spherical colloids. These materials, unfortunately, do not exhibit any particularly interesting optical, nonlinear optical or electro-optical functionality. In this regard, it is necessary to develop new methods to either dope currently existing spherical colloids with functional components or to directly deal with the synthesis of other functional materials. Second, formation of complex crystal structures other than closely packed lattices has been met with limited success. As a major limitation to the self-assembly procedures described in this chapter, all of them seem to lack the ability to form 3D lattices with arbitrary structures. Recent demonstrations based on optical trapping method may provide a potential solution to this problem, albeit this approach seems to be too slow to be useful in practice.181-184 Third, the density of defects in the crystalline lattices of spherical colloids must be well-characterized and kept below... 

These examples of functionalization of carbon nanotubes demonstrate that the chemistry of this new class of molecules represents a promising field within nanochemistry. Functionalization provides for the potential for the manipulation of their unique properties, which can be tuned and coupled with those of other classes of materials. The surface chemistry of SWCNTs allows for dispersibility, purification, solubilization, biocompatibility and separation of these nanostructures. Additionally, derivatization allows for site-selective nanochemistry applications such as self-assembly, shows potential as catalytic supports, biological transport vesicles, demonstrates novel charge-transfer properties and allows the construction of functional nanoarchitectures, nanocomposites and nanocircuits. 

Scaffolds can be made from natural or synthetic materials. Such materials fall under the category of biomaterials. A biomaterial can be considered a single element or compound, which is a composite or mixture of elements, and is synthesized or derived to be used in the body to preserve, restore, or augment the structure or function of the body. Examples of natural materials for scaffold construction are extracellular matrix, collagen, fibrin, and polysaccharides (e.g., chitosan or glycosaminoglycans). Natural materials, unless they are obtained from the patient who receives the neo-organ implant, will cause an immunogenic response. This is not always the case with synthetic materials. 

A particularly well studied example of functional amyloid is provided by Curli assembly (53). Curli amyloids are assembled by bacteria such as Escherichia coli and Salmonella. Once assembled on the extracellular surface, Curli amyloid fibers function as natural ceU adhesion molecules that link together bacterial cells into robust cellular networks of biofilms. Other examples of functional amyloids include the silk fibers observed commonly in spider webs the Chorion proteins of egg shells Factor XII, which is an activator of the hemostatic system and other naturally produced adhesives and materials (54). 

As mentioned above, it has recently been demonstrated that ferrocene systems, especially polymers, are potentially excellent NLO materials [4]. Two examples of such materials obtained by polycondensation are described here. New monomers, namely 33 and 34, have been prepared (as shown in Scheme 10-13) by selective functionalization of the cyclopentadienyl rings of ferrocene [40]. 

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