Using acetone-water as medium and 2,2′-azobisisobutyramidine dihydrochloride(AIBA) as cationic radical initiator, three emulsifier-free cationic copolymer nanoparticles were synthesized under microwave irradiation from styrene with methylmethacrylate, diacetoneacrylamide and β-hydroxyethyl-methacrylate respectively. The latexes were excellently stable. The particles were characterized by IR, TEM, LLS. The influence of comonomer content and hydrophilicity on the hydrodynamic radius of copolymer nanoparticles was discussed. The results indicated that the average of copolymer particle decreased with increase of the concentration and hydrophilicity of the comonomer.
Polymerization of styrene and methylmethacrylate was conducted in the presence of seeds and microwave irradiation. The particles were characterized by laser light scattering and transmission electron microscopy. Making comparison between two kinds of microsphere formation processes, we have obtained some information on the mechanism of the particle formation. For polystyrene the process was mainly conducted on the seeds. However, for polymethylmacrylate at the lower concentration range, the process was mainly conducted in the solution, in contrary, at higher concentration, it occured mainly on the seeds.
