A new method has been developed to prepare exfoliated poly(methyl methacrylate)/clay nanocomposites by in situ polymerization of methyl methacrylate (MMA) in the presence of triethylaluminum (TEA)-modified clay. The dispersed behavior of the clay in the PMMA matrix is identified by using X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV/vis transmission spectroscopy. The PMMA/clay nanocomposites are found to retain over 80% transparency, important for optical applications. Compared to neat PMMA, all these nanocomposites show enhancement of glass transition temperature (T g) and decomposition temperature. The storage modulus (E′) and tensile properties of the nanocomposites are also significantly enhanced by incorporating clay into the PMMA matrix and increased as the amount of clay increased. The tensile strength of nanocomposites is up to 70 MPa for 7.26 wt % clay content, and the tensile modulus shows a 20% higher value than that of neat PMMA.

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Ecofriendly procedure for silver–silver chloride nanoparticle synthesis with different reaction parameters tested.

We developed a series of nonchelated monodentate benzimidazole nickel complexes, bis [2-(2,6difluorophenyl) 4), upon activation with methylaluminoxane (MAO), which are found to be highly active for vinyl polymerization of norbornene (Nb). The polymerization activity displayed by 4 is as high as 1.68 × 10 9 g of PNb‚mol Ni -1 ‚h -1 at very high Nb/Ni ratio of 1 × 10 5 . Moreover a small amount of MAO is required to achieve such activity with high yield. The comparable high activity of 4.96 × 10 8 g of PNb‚mol Ni -1 ‚h -1 for the simplest complex 3 reveals the significance of nonchelation in this catalyst series. It is observed that the use of toluene as solvent inhibits the catalytic activity strongly. The in situ NMR analyses indicate that the ligand is still intact with the active species and hence the difference in activity is indeed being associated with the change in ligand.

Combinatorial technology has been evaluated as the revolutionary approach to overcome the limitation of conventional research and to advance research in the development of novel materials and catalysts. For the past decade, because of the advance in library synthetic method and characterization tools, combinatorial and high-throughput methodology surprisingly matured and nowadays has been extended to discovering novel olefin polymerization catalysts. However, despite such an advance, the characterization methodology did not keep pace with the increase in library density and limited the application of combinatorial technology. Therefore, in combinatorial technologies, the development of novel characterization methods is urgent and very important. In this review, we introduce several characterization tools and synthetic apparatus that are currently applied to discovering inorganic materials and catalysts using combinatorial technology, and consider how to overcome these limitations.