Monodisperse micrometer-size carboxyl-functionalized polystyrene particles obtained by two-stage radiation-induced dispersion polymerization

Monodisperse carboxyl-functionalized polystyrene particles with range of 600–2100 nm were synthesized by two-stage radiation-induced dispersion polymerization of styrene in ethanol/water media using poly (vinylpyrrolidone) (PVP) as the stabilizer and itaconic acid (IA) as a functional comonomer. The resulting carboxylated polystyrene (PS) particles had a narrower size distribution compared with those obtained by one-stage dispersion polymerization. In the two-stage method, the presence of additional IA in the second reaction may help to prevent secondary nucleation and to promote the formation of monodisperse particles. The effects of concentration of IA, PVP and solvent polarity on the particle size and size distribution were discussed in detail. The characterizations (particle size and size distribution, locus of the carboxyl groups) of carboxylated PS microspheres were carried out by the scanning electron microscope (SEM), particle diameter measure and analysis system and conductometric titration. In order to examine the surface carboxylation of PS particles, P (St-co-IA)/Co composite microspheres were prepared by repetitious interface deoxidized reactions. The composite microspheres were characterized by transmission electron microscope (TEM), SEM, X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD).