The synthesis of composite particles responsive to electric and magnetic fields

A new route to produce composite particles showing electric and magnetic response is presented in this paper. The particles comprised of Fe₃O₄/PSt magnetic polymer spheres as core and amorphous titania as shell were prepared in two steps. This method avoids three or more steps of multi-coating on glass spheres. The morphology and the structure of the particles were characterized by SEM, FT-IR and TG-DTA. The measured dielectric constant and conductivity of the composite particles were approximate to that of the pure amorphous titania particles. Meanwhile, the transmittance of the aqueous suspension of composite particles can reach 90% within 900 s under magnetic field, in contrast to that of 60% under no magnetic field. Furthermore, the particles suspended in silicon oil can quickly form chains structure when a 0.6 kV/mm electric or 1500 Gs magnetic field strength was applied. This indicates that the as-prepared composite particles are responsive to both electric and magnetic fields.