Copper (I) ion stabilized on Fe3O4-core ethylated branched polyethyleneimine-shell as magnetically recyclable catalyst for ATRP reaction

Branched polyethyleneimine (bPEI) was used to modify the surface of Fe3O4 nanoparticles coated with silica layer, and then, it was treated with ethyl iodide to prepare Fe3O4@SiO2@Ethylated-bPEI. In the next step, the yolk-shell structure was gained by selectively etching the SiO2 middle layer. Finally, copper(I) was introduced to the yolk-shell Fe3O4@Ethylated-bPEI and the activity of the catalyst was evaluated for atom transfer radical polymerization (ATRP) of styrene, led to obtain the well-defined polymer with relatively low polydispersity. The toxicity of the residual copper in the polymer product was a limiting issue for applicability of ATRP reactions especially for biological purposes. In this report, the copper content in the polymer was reduced to the excellent value of 1.1 ppm. Moreover, the magnetic isolation, recyclability, and remove the need for an external ligand were other advantages of the synthesized catalyst which makes it suitable for employing in ATRP reactions. (C) 2015 Wiley Periodicals, Inc.