Morphology control, importance

The potential of morphologically controlled metal nanoparticles should be expanded by further improvement of their preparation method. It is highly required to develop preparation methods to obtain a better morphological control, i.e., perfect facet control on the particles of optional size. Better morphological control of metal nanoparticles is expected to be achieved in near future and the obtained metal particles will find new exciting applications, not only in catalysis but also in other technically important fields. 

The use of tailor made additives holds great promise in the area of crystal growth and morphology control. The routine selection and use of these type of additives will require a fundamental understanding of the mechanism which the additives work on a molecular basis. At the same time, the effect of solvent molecules on the crystal growth process is another related and important problem. In both instances, the relationship between internal aystal structure, aystal growth rate, solvent and impurities are needed to predict the habit of a crystal and thus allow seleaion of the proper conditions and components required to obtain a desired habit... 

Many synthetic membranes are known to be useful for separation of water and various sizes of solutes from aqueous solutions by selective separation, for examples reverse osmosis, ultrafiltration, dialysis and so on 1 7). The permeability is much dependent on both of chemical and physical structures of the membranes. The choice of the barrier materials for membranes and the control of their morphology are important to get effective permselective membranes. 

Morphology control in a mixing operation is, therefore, very important for utilizing the properties of a blended-in high-performance polymer. It appears that continuity of one or both phases is often essential to obtain optimum properties. This continuity is generated in the blending process, though, unfortunately, not much is known of the ways to control it. 

Crystallite morphology prediction and morphology control are important for several kinds of applications. Zeolite membranes can require alignment of many distinct crystallites, this being facilitated by having uniformly shaped... 

For industrial applications, the particle size, morphology, and texture of the mesoporous material are important, which include several critical points such as mechanical stability and macroscopic shapes with well defined properties. Morphology control is one of the most interesting issues in the research field of mesoporous materials. It plays a very important role in understanding the basic synthesis mechanism. 

Morphology control is indispensable in many of the advanced applications envisioned for functional mesoporous materials (54, 267). Permselective membranes, micro-spheres, or monoliths are important for sorption, separation, and chromatography purposes. Porous thin films or fibrous structures are relevant for electronics, optics, low fe-dielectrics, and sensing applications. Colloidal particles or nanospheres are preferred for biomedical systems to be used in drug delivery or magnetic resonance imaging (MRl) with contrast agents. 

The nanoscale materials considered in this chapter are solid materials with primary particles sizes ranging from 1 to 100 nm (10 to 1000 A), as defined in Chapter 1 of the first edition (1). Materials referred to as powders are simply classified through observation rough powder (1 mm to 40 p.m, optical microscope), fine powder (40 p,m to 1 p,m, optical microscope), and superfine powder (<1 p,m, only visible by electron microscope). The latter, superfine powder or nanoparticles, may correspond to the primary particle. These nanoparticles are usually in the form of smoke, combusted particulates, and dispersed primary particles. Some rough and fine powders may be composed of primary particles if the surface area is high. The microstructure of a pellet or powder is important, because the chemical reaction starts from the surface (favored for small crystals) and gas diffuses through the void channels. The morphology controls the reaction rate, which is one of the main concerns in this chapter. 

The morphology control has proved to be extremely important for the optimization of PSCs. Recent developments in device architectures have also shown promising potential for further increasing the performance of PSCs. 

Important features of the sol-gel method are better homogeneity compared to the traditional ceramic method, high purity, lower processing temperature, more uniform phase distribution in multicomponent systems, better size and morphological control, the possibility of preparing new crystalline and non-crystalline materials and, lastly, easy preparation of thin films and coalings. The sol-gel method is widely used in ceramic technology and the subject has been widely reviewed [1-3]. 

X. Yang, J. Loos, Towards high-performance polymer solar cells the importance of morphology control. Macromolecules, 40, 1353-1362 (2007). 

To achieve good toughness, required for many applications, impact modifiers are added to PVC. Chlorinated polyethylenes, ethylene-vinyl acetate copolymers, styrene-methyl methacrylate grafted elastomers, vinyl rubbers, and polyacrylates are the most frequently used (316). These polymers are blended together with other additives. Blending conditions are extraordinary important for morphology control and consequently for final properties of the blends. 

Morphology. Control of the morphology of each PVC grain is the main parameter controlling the quality of a PVC resin. This subject covers mean grain size, grain size distribution, and, most important of all, porosity (cold plasticizer absorption) and bulk density, which are closely interrelated. 

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