Effect of Fe3O4 particles on multi-hollow morphology of poly(HEMA-divinylbenzene-styrene) microspheres prepared by Pickering suspension polymerization

Hydroxy-functionalized polymers have been synthesized by Pickering suspension polymerization of 2-hydroxyethyl methacrylate (HEMA) with styrene (S) and divinylbenzene (DVB) in the presence of hydrophobic Fe3O4 particles.The obtained polymer microspheres were characterized using different instrumental techniques (optical microscopy, scaning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), diffuse reflection ultraviolet-visible spectroscopy (DR UV-Vis), inductively coupled plasma-optical emission spectrometry (ICP-OES), dynamic light scattering and thermal analyses) and then modified to immobilize the complexes of palladium(II) with the tetradentate ligands based on salicylaldehyde, epichlorohydrin and 2-picolylamine. The resulting polymer supported complexes were preliminarily examined as catalysts in the model Suzuki reaction between 4-bromotoluene and phenylboronic acid. It was found the polymer particles obtained as a result of the performed polymerization have composite nature and are characterized by a unique multi-hollow morphology with pores up to 50 µm in size. An advantageous effect of the Fe3O4 particles embedded in the synthesized polymer microspheres on the activity of palladium catalysts has been noted