Synthesis of cross-linked core-shell polymer particles by free-radical dispersion copolymerization of 4-vinylpyridine with polystyrene macromonomers in nonaqueous media

摘要

Cross-linked core-shell polymer particles were synthesized by free-radical dispersion copolymerization of 4-vinylpyridine(4VP)and various kinds of cross-linking reagents with methacryloyl-terminated polystyrene(PS)macromonomers in nonaqueous media such as 1,4-dioxane and cyclohexane.Well-defined particles were obtained by copolymerization of 4VP with ethylene glycol dimethacrylate(EGDM)in a dixoane medium.The particle diameters(D_n=40-990 nm)decreased drastically both with increasing the feed concentration ratio of macromonomer to 4VP,[PS-M]/[4VP],and with increasing molecular weight of PS-M macromonomers.The particle size distribution (D_w/D_n)was in the range 1.02-1.10.PS-M macromonomers acted not only as comonomers but also as stabilizers.The particle diameters obtained in dioxane were smaller than those obtained in cyclohexane.Thus,we observed a tendency to smaller particle size as the media became more soluble for PS-M macromonomer.