Controlling the heterocoagulation process for fabricating PS–CoFe2O4 nanocomposite particles

Most ordinary polystyrene (PS) microspheres without any surface modification and hard magnetic cobalt ferrite (CoFe2O4) nanoparticles were, respectively, used as large host particles and small guest particles in a heterocoagulation system. In order to achieve a regular heterocoagulation for fabricating PS–CoFe2O4 composite particles having tailored morphology, chief attention was focused on controlling over the heterocoagulation process instead of the surface modification of the polymer microspheres. A process was adopted, which included blending the two colloids at pH 1 and then, adjusting the pH value of the blending colloid to an optimal range of 2–4 under a suitable weight ratio of the two kinds of particles. The results of TEM, SEM, ζ-potential, TGA and magnetization measurements have confirmed the high density of coverage of the CoFe2O4 nanoparticles onto the surface of polystyrene particles.