Organic/inorganic hybrid composed of modified polyacrylamide grafted silica supported Pd nanoparticles using RAFT polymerization process: Controlled synthesis, characterization and catalytic activity

Reversible addition-fragmentation chain transfer (RAFT) polymerization was utilized for the preparation of polyacrylamide brushes grafted onto silica particles (SiO2-g-PAAm) via grafting to and grafting from approach in a controlled manner. Control of both the polymer's molecular weight and the density of grafted chains can be achieved by these methods. The polymer grafted silica was further modified to convert it to phosphinite ligand. Complexation of this ligand with Pd(OAc)(2) was performed in order to obtain the Pd catalytic system. Various techniques such as FT-IR, TGA, XRD and electron microscopy systems such as SEM and TEM were conducted as characterization methods. Moreover, X-Ray photoelectron spectroscopy (XPS) of the catalyst disclosed the binding energy of Pd in zero oxidation state properly. This organic-inorganic hybrid catalytic system showed proper activity in Heck coupling reaction. The catalyst was successfully reused in repeating cycles with negligible change in its efficiency. Characteristic of the catalyst such as size and shape, chemicophysical stability and the structure of catalyst are retained almost unchanged even after successive reactions. (C) 2017 Elsevier B.V. All rights reserved.