Small molecule materials

Polymer supported reagents, catalysts, protecting groups, and mediators can be used in place of the corresponding small molecule materials (Sherrington, 1991 Sundell and Nasman, 1993). The reactive species is tightly bound to a macromolecular support which immobilizes it. This generally makes toxic, noxious, or corrosive materials much safer. The use of polystyrene sulfonic acid catalyst for the manufacture of methyl r-butyl... 

Just as many small-molecule materials, polymers also form glasses [4]. Actually, most polymeric materials of everyday use are made of polymer glasses, polystyrene (PS) cups or compact discs made of polycarbonates, for instance. In many respects polymer glasses are very similar to small-molecule glasses, and there is nothing special about them. However, on the other hand, the special aspects of polymer materials allow specific studies beyond characteristic studies on small-molecule glasses. 

In Section 13.2, we introduce the materials used in OLEDs. The most obvious classification of the organic materials used in OLEDs is small molecule versus polymer. This distinction relates more to the processing methods used than to the basic principles of operation of the final device. Small molecule materials are typically coated by thermal evaporation in vacuum, whereas polymers are usually spin-coated from solution. Vacuum evaporation lends itself to easy coaling of successive layers. With solution processing, one must consider the compatibility of each layer with the solvents used for coating subsequent layers. Increasingly, multilayered polymer devices arc being described in the literature and, naturally, hybrid devices with layers of both polymer and small molecule have been made. 

Looking at Table 7.8 it is readily seen that in terms of fitness eukaryotes and prokaryotes each have advantages and disadvantages so that the best solution for total optimal energy capture is coexistence assisted by cooperation not competition. If life could have started from a situation where there had been an ample supply of sufficiently reduced basic small molecule materials and energy and no reduction but only molecular combination was required, it may well have been that anaerobic prokaryotes would have remained exclusively successful. They are still in abundance on the Earth. There would have been no need to reject oxidised materials, and increase in the number of compartments would have had little advantage since the observed chemically necessary syntheses (see Chapter 4) are simply... 

O Organic Small Molecule Materials for Organic Light-Emitting Diodes... 

A bewildering array of materials has been used as emitters in SMOLEDs since this early work on Alq3. In the following sections, we will present a brief review of host-guest emitter materials and give a perspective description of all the current state-of-the-art small molecule materials for emission at the three primary colors needed for full-color display applications. 

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