SÍNTESE DE MICROESFERAS MAGNÉTICAS A PARTIR DE UMA MATRIZ POLIMÉRICA DERIVADA DO POLI(TEREFTALATO DE ETILENO) (PET) RECICLADO

Abstract

In this study, magnetic microspheres were produced for the first time from chemical recycling of post-consumer poly(ethylene terephthalate) (PET), obtained through catalyzed glycolysis method. The effects of the reaction time and the amount of catalyst were evaluated and according to the experimental results, the best condition for the glycolysis of PET was found to be 2 hours of reaction time and 10.0% for the ratio catalyst/PET. High performance liquid chromatography (HPLC) analysis and nuclear magnetic resonance of proton (1H NMR) was confirmed that bis(2-hydroxyethyl) terephthalate (BHET) was the main product of the depolymerization reaction. The BHET was chemically modified by reaction with glycidyl methacrylate (GMA). The reaction was been performed at 30 and 60°C in dimethylsulphoxide (DMSO) and N, N, N ', N' tetramethylethylenediamine -catalyzed (TEMED). 1H NMR and 13C NMR analyses indicated the insertion of vinyl groups derived from GMA in the BHET structure, and the modification occurred to a greater extent at 60°C. The reaction occurred, predominantly, via opening of the epoxide ring. Hydrophobic magnetite nanoparticles (Fe3O4@AO) were synthesized in order to include magnetic properties to the polymeric microspheres. Nanoparticles were produced via chemical coprecipitation method, and were characterized by dynamic light scattering (DLS), X-ray diffraction (XRD), magnetization (VSM) and infrared spectroscopy (FTIR) techniques, which showed that magnetite was coated with oleic acid and presented a superparamagnetic behavior. The magnetic microspheres were obtained by the suspension polymerization method performed at 80°C. Modified BHET monomer was used for the synthesis of the polymeric matrix and dichloromethane was used as diluent/porogenic agent. Scanning electronic microscopy (SEM) images showed a spherical particle containing pores and iron uniformly distributed on its surface and that the instability of the dispersion during the modified BHET polymerization reaction resulted in a large number of particles with irregular morphology. The mixture of GMA and modified BHET improved the spherical shape of the particles, and it can reduce the effect of boiling dichloromethane, identified as a possible cause of instability of the organic phase droplets. The results have shown that further studies must be carried out on the dispersion stability to produce magnetic microspheres with the polymeric matrix derived from recycled PET, which may be applied in future removal of pollutants from an aqueous medium.