Abstract:

Using PVP as the stabilizer and AIBN as the initiator, monodisperse PAM microspheres sized in submicrometer were prepared in ethyl acetate/ethanol media by dispersion polymerization method. In the early period of the dispersion polymerization, auto-accelerate phenomenon was observed, and molecular weight gradually increased with the increase of the conversion because of the gel effect. The study on the FTIR spectrum of PAM and the effects of the concentrations of stabilizer on final increment ratio reveal that adsorption stabilization mechanism and graft stabilization mechanism are concurring in this system and the latter is dominant. The influences of polymerization parameters, such as concentration of stabilizer, initiator, monomer and solvent composition on the particle size and size distribution were also investigated. The size distribution is narrow when the volume ratio of ethyl acetate to ethanol ranges from 5∶5 to 7∶3. Particle size decreases with the increase of the concentration of stabilizer and the decrease of the concentration of initiator, moreover, monodisperse microspheres cannot be obtained when the concentration of monomer is too high or too low.

Key words: Dispersion polymerization, Polyacrylamide, Microsphere with submicrometer size