Preparation And Characterization Of Cationic Monodisperse Polystyrene Microspheres

In this paper, three kinds system of dispersion polymerization and a soap-freeminiemulsion polymerization were designed:(1) the cationic functional monomer DMC wasintroduced into the dispersion polymerization in the absence of stabilizer. The polymerizablemonomer DMC was an effective cationic functional monomer. Monodispersed cationic PSmicrospheres with particle diameter of1.06~1.62μm were prepared. PS particles withdiameter of1.36μm and the despersin coefficient of0.02were generated as regeant dosagewas as follow: V(St)=4ml, V(DMC)=0.1ml, and m(AIBN)/m(St)=1wt%.(2) Thedispersion polymerization in the absence of stabilizer was stabilized by charge repulsioneffect and the charge was supplied simply with the cationic initiator V-50. The averageparticle size of PS microspheres was increased with the dosage of initiator increasing until nosphereical PS microspheres were formed. With increasing monomer amount, the PS particlesize was augmented, and the distribution coefficient also basically was increased. As thecontent of water in the dispersion medium increasing, PS particle size was decreased,however particle size distribution showed a narrowing trend. When the water volume is morethan10mL, PS could not form the ball in the system.(3) HEA was introduced into thedispersion polymerization in the absence of stabilizer to realize the PS microspheres hydroxylfunctionalization. The hydrophilic groups of HEA were in favor of stabilizing nucleation inno stabilizer system of the dispersion polymerization, and the size of PS microspheres wasincreased as comonomer adding. However monodisperse PS microsphere could be obtainedwhen the dosage of initiator was at0.5wt%~2.0wt%range.(4) We used ultrasonic wave tocarry on the homogenization of miniemulsion in the soap-free miniemulsion polymerization,and the charge supplied with the cationic initiator V-50engendered electrostatic repulsioneffect. Through soap-free miniemulsion polymerization, cationic monodisperse PS particleswere synthetized with the particle size in the range of0.12to0.52μm and gained optimalminiemulsify conditions, for example, ultrasonic power was350W, and ultrasound time was4min. When the concentration of the initiator was in a wide range, monodisperse PS microspheres could be prepared by soap-free miniemulsion polymerization. Moreover, thecharge repulsion effect had a certain role to stabilize soap-free miniemulsion system. Theresults were characterized by SEM, XPS,~1H-NMR, GPC et al. And we discussed the stabilitymechanism of each polymerization.