Matrix polymer LEDs mixed with

Suppression of the aggregate emission is now possible by two quite different means. At first, the aggregate emission could be almost completely shut out by simply mixing the LPPP 15 with a matrix polymer. LEDs with 1% LPPP 15 in poly(vinyl carbazole) PVK as emitter material are characterized by a pure blue light emission with a quantum efficiency of ca. 0.15% in layer formation (ITO/1% LPPP 15 in PVK/Ca). Polystyrene (PS) is unsuitable as matrix in this case the emitter LPPP must be used with a much greater dilution (0.001%) in order to suppress the yellow emission band. At this level of dilution of the chromophore, the formation of efficient, stable emitting LEDs was no longer possible. 

Unlike melt intercalation, a layered silicate is mixed with monomer before polymerization takes place with in situ polymerization. This method was developed by Toyota researchers [27,28], in which electrostatically held 1-nm thick layers of layered alumina silicates were dispersed in a polyamide matrix on a nanometer level, which led to an exponential growth in the research endeavors, in layered silicate nanocomposites. These nanocomposites were based on the in situ synthesis approach in which a monomer or monomer solution was used to swell the filler interlayers, followed by polymerization. With this process, one can control the nanocomposite morphology through the combination of reaction conditions and clay surface modification. The in situ polymerization method is especially important for insoluble and thermally unstable polymers, which solution blending or melt blending technique cannot process. 

Most of the more recent research has focused on developing membrane materials with a better balance of selectivity and productivity (permeability) as that seems the most likely route for expanding the use of this technology. There appear to be natural upper bounds [9,10] on this tradeoff that limit the extent of improvement that can be realized by manipulating the molecular structure of the polymer used for the selective layer of high-flux membranes, at least in many cases. This has led to interest in nonpolymeric and so-called mixed-matrix materials for membrane formation [8] however, at this time, polymers remain the materials of choice for gas-separation... 

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