Green Nanocatalyst-Palladium nanoparticles inside polymer matrix make catalysts easier to retain and recycle
Metal catalyst recoverable at the end of a reaction by simple filtration is done by attaching metal catalysts to an insoluble polymer support. Conventionally, there is trend of attaching a metal catalyst to an insoluble polymer resin. But, the metals were invariably leached out of the polymer after some time. Hence catalysts were slowly lost after the chemical reaction is over.
Green Chemistry scientist approached differently, they integrated the metal into the polymer matrix which can trap metal more efficiently. Researchers started this by soluble polymer precursor instead of an insoluble resin. The insoluble resin contains an imidazole units, which is very efficient chemical structure well-known for binding strongly with metals such as palladium. An imidazole units have to self-assemble around atoms of the metal only after adding the palladium .So an insoluble composite material is formed .All this process is called "molecular convolution".
Scanning electron microscopy (SEM) result shows that final polymer contains palladium globules having a diameter of 100-1,000 nanometers which aggregated into a highly porous structure reminiscent of a tiny bathroom sponge. Moreover this insoluble material like a sponge has an ability to simply capture substrates and reactants from the solution. Finally reaction is carried out with metal species embedded in the sponge.
By the use of green chemistry we can embed palladium nanoparticles inside a self-assembled polymer matrix which makes catalysts easier to retain and recycle catalysts. Eventually this will provide a safe and highly efficient chemical process. Moreover in the future this method is accepted by chemical industry people for various industrial chemical processes.
You can find more information on this long lasting green nanocatalyst in the research paper published by Shaheen Sarkar called "A highly active and reusable self-assembled poly(imidazole/palladium) catalyst: allylic arylation/alkenylation" in "Angewandte Chemie International Edition 50" journal published in 2011
Finally I would say this highly active and reusable self-assembled poly(imidazole/palladium) catalyst would provide a new hope to get 100% reusable/recycled catalyst. i.e longer lasting chemical catalyst.
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