Abstract: Polychloroprene-polymethylmethacrylate(PCR-PMMA) composite latex particles have been prepared through the seed emulsion polymerization with polychloroprene latex(Pa) and methyl methacrylate(Pb) as the seed and monomer, respectively. Thermodynamic analysis results showed that when Φb(volume fraction of polymer b)＜0.69, the Pa-Pb core-shell latex particles and (Pa＋Pb) separated latex particles were formed; while when Φb＞0.69, the inverted Pb-Pa core-shell latex particles and Pa-Pb core-shell latex particles were formed. Kinetic analysis results showed that the initiator type, the monomer feed type, crosslinking of the seed latex particles, and the monomer-to-rubber ratios were major factors influencing the particle morphology. When potassium persulfate was used as the initiator, the monomer-starved conditions led to the formation of normal core-shell particles, whereas flooded-feed MMA could not favor in formation of typical core-shell particle. While when azobisisobutyronitrile(AIBN) was used as the initiator, it led to the formation of inverted core-shell particles no matter if monomer-starved or flooded condition was used. Crosslinking of the polychloroprene seed particles was found to favor to form obvious core-shell PCR-PMMA particles. With the monomer-to-rubber ratio increasing, the shell layer turned thicker, the composite latex particle still showed core-shell structure, which was in agreement with the predicted results of thermodynamic analysis. The inverted core-shell PCR-PMMA composite latex particles were gradually changed to interpenetrating structure as the amount of monomer was increased when AIBN was used.

Key words: latex particle morphology, thermodynamic, kinetic, seeded emulsion polymerization