Controlled material properties

Figure 1.4. Catalysts are nanomaterials and catalysis is nanotechnology. If we define nanotechnology as the branch of materials science aiming to control material properties on the nanometer scale, then catalysis represents a field where nanomaterials have been applied commercially for about a century. Many synthetic techniques are available to...

Knuuttila, H., Lehtinen, A. and Nummila-Pakarinen, A. Advanced Polyethylene Technologies - Controlled Material Properties. Vol. 169, pp. 13-27. 

Zeolite catalysts play a vital role in modern industrial catalysis. The varied acidity and microporosity properties of this class of inorganic oxides allow them to be applied to a wide variety of commercially important industrial processes. The acid sites of zeolites and other acidic molecular sieves are easier to manipulate than those of other solid acid catalysts by controlling material properties, such as the framework Si/Al ratio or level of cation exchange. The uniform pore size of the crystalline framework provides a consistent environment that improves the selectivity of the acid-catalyzed transformations that form C-C bonds. The zeoHte structure can also inhibit the formation of heavy coke molecules (such as medium-pore MFl in the Cyclar process or MTG process) or the desorption of undesired large by-products (such as small-pore SAPO-34 in MTO). While faujasite, morden-ite, beta and MFl remain the most widely used zeolite structures for industrial applications, the past decade has seen new structures, such as SAPO-34 and MWW, provide improved performance in specific applications. It is clear that the continued search for more active, selective and stable catalysts for industrially important chemical reactions will include the synthesis and application of new zeolite materials. 

Advanced Polyethylene Technologies— Controlled Material Properties... 

The nonperiodic structure of surface defects such as steps makes them very difficult, if not impossible, to investigate by commonly employed diffraction techniques, and real-space imaging becomes mandatory. In this respect, STM, with its capability of imaging electrode surfaces in situ with atomic resolution, provides a unique possibility of studying processes for which surface imperfections play a key role, such as metal deposition and dissolution [14-20], oxide formation [21-24], and corrosion [25-29]. The additional capability of STM to control material properties... 

We shall use the above four conditions as a basis for analysis and comparison of the various detector materials and of the two modes, photovoltaic and photoconductive, in the remainder of this chapter. Conditions 1-4 provide a convenient framework for discussing the detector materials, because the parameters on the left sides of the four relationships are directly related to measurable and controllable material properties. 

The addition of the second component therefore enhanced the gelation process for dendron A, but hindered the gelation process for dendron B. In siunmary, the gel-phase materials properties of the two dendrons responded in opposite ways to the presence of a diamine additive. This is a remarkable example in which dendritic generation and the use of a second (supramolec-ular) component can both control materials properties. This effect can be considered as orthogonal dendritic and supramolecular control. It was argued that, in the future, these systems may be exploited to develop switchable and highly controllable gel-phase materials. 

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