Preparation and characterization of poly(MMA-EGDMA-AMPS) microspheres by soap-free emulsion polymerization

The poly(methyl methacrylate-ethylene glycol dimethacrylate-2-acrylamido-2-methylpropanesulfonic acid) [poly(MMA-EGDMA-AMPS)] microsphere was produced by a soap-free emulsion polymerization of MMA, EGDMA and AMPS. The chemical composition, morphology, particle size distribution and properties of the obtained microspheres were characterized by energy dispersive spectrometer (EDS), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), a laser particle analyzer and thermogravimetric analysis (TGA). Results showed that the microspheres had a high-quality spherical morphology, irrespective of the components, and their particle sizes mainly ranged from 10 mu m to 70 mu m. The microspheres were thermally stable up to 190 degrees C. As the AMPS loading was increased, the synthetic yield rate decreased and the water uptake increased. The optimum synthetic yield rate and water uptake were obtained at a 2.0 wt% AMPS. In addition, the selected microspheres with a diameter of approximately 25 mu m provided an effective plugging, and the plugging rate was up to 80%. This study demonstrated that the plugging behavior of microspheres was due to their deformation, migration and aggregating properties in the plugging process, which made them potential materials for modifying the porous reservoir to enhance oil recovery in petroleum engineering.