Fabrication of well-defined magnetic microporous polymeric monoliths using simple non-aqueous emulsification technique

Abstract

The current work describes a novel route for preparation of robust polymeric monolithic structures exhibiting magnetic properties via emulsification of a polar glycerin oil in a polymerizable hydrophobic oil of styrene as oil/oil (o/o) emulsion technique. Hydrophilic magnetite nanoparticles were first prepared via the co-precipitation method and then converted to organophilic using oleic acid as a surface coating material. The FT-IR provided evidence on the covering of the particle's surface and also revealed some hydrophilic OH groups co-exist, implying a probable amphiphilic character is acquired. The organophilic particles act efficiently as Pickering stabilizers for glycerin/styrene emulsion systems. Styrene, a polymerizable oil, could be subsequently polymerized at 70 °C in the presence of an oil-soluble thermal initiator such as 1,1-azobiscyclohexanecarbonitrile (vazo). Scanning electron microscopy (SEM) confirmed the formation of well-defined, highly porous polymeric monoliths, in which the distribution of the pores within the monolith further supported that they were prepared via well-emulsified glycerin drops in the styrene phase as a precursor. Additionally, the EDX revealed the presence of the iron element distributed evenly within the monolith. The thermogravimetric analysis (TGA) revealed a slight resistance to thermal degradation over a narrow range up to 150 °C with respect to pure polystyrene, whereas beyond this temperature the degradation behavior proceeded almost typically as for pure polystyrene. The ferromagnetic resonance spectroscopy (FMR) indicated the acquisition of the magnetic property by the produced monolith structure. For the best of our knowledge, it is the first article of its type investigating the fabrication of polymeric monolithic structures from non-aqueous emulsions.