Functionalized Polystyrene Particles Obtained By Radiation-Induced Dispersion Polymerization

In this thesis, we focus on the preparation of monodisperse functionalized polystyrene particles. The main contents embrace three aspects which are summarized as follows:1. Monodisperse carboxyl-functionalized polystyrene particles with range of 0.6–2.1μm were synthesized by two-stage radiation-induced dispersion polymeri- zation 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 stage 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.In functional polymer particles, the introduction of carboxyl groups into polymer structures could provide chemically reactive sites which increase hydrophilicity of the polymer particles. The carboxyl group density on the surface of the copolymer particles was determined directly by conductometric titration. It was found that partition of the functional group densities dissolved in the supernatant, physically adsorbed and chemically anchored on the surface of the copolymer particles, and buried within the copolymer particles was not constant with various concentration of comonomer.2. In order to examine the functionality of the particles, P (St-co-IA)/Co3O4 composite microspheres were prepared by repetitious interface reactions. After monodisperse carboxyl-functionalized polystyrene particles were added into the ammonia aqueous solution of Cobalt chloride, Co2+ can be adsorbed on the polystyrene particles surface via electrovalent bond, then Co could be obtained by interface reduction reactions under gamma-ray irradiation.3. Polystyrene coating of Fe3O4 particles by radiation-induced dispersion polymerization was studied. The coating process was carried out in ethanol/water media, poly (N-vinylpyrrolidone) as stabilizer, and divinyl benzene as a cross-linking reagent. The cross-linking reagent played an important role in the dispersion polymerization. A continuous and dense polymer layer coating was formed on the Fe3O4 particles in the presence of the cross-linking reagent, and the layer coating on the Fe3O4 particles was formed by the adsorption of polymer sols that joined together to form the layer coating.