Ultrasound-assisted synthesis and characterization of magnetite nanoparticles and poly(methyl methacrylate)/magnetite nanocomposites

Poly(methyl methacrylate)/magnetite (PMMA/Fe3O4) nanocomposites were prepared with a two-step technique involving sonication. Fe3O4 nanoparticles were synthesized by ultrasound-assisted co-precipitation, and then PMMA/Fe3O4 (1–5 wt%) nanocomposites were synthesized via ultrasound-assisted in-situ emulsion polymerization. Best physical properties of the nanocomposites for different Fe3O4 loadings were: tensile strength (2 wt%) = 40.28 MPa, Young’s modulus (2 wt%) = 2.4 GPa, percentage elongation (2 wt%) = 2.24%, glass transition temperature (2 wt%) = 122.5 °C, thermal inflection point (2 wt%) = 383 °C, electrical conductivity (5 wt%) = 2.0 × 10−13 S/cm, coercivity = 59.85 Oe (2 wt%), magnetic saturation (5 wt%) = 5.12 emu/g, magnetic remanence (5 wt%) = 0.56 emu/g, and electromagnetic interference shielding effectiveness (5 wt%) = 1.45 dB. This unique combination of physical properties at relatively low Fe3O4 loading is attributed to ultrasound-mediated uniform dispersion of the nanofiller in the polymer matrix.