Preparation of BA/St/AM copolymer latexes by ultrasonic soap-free emulsion polymerization

Through ultrasonic emulsifier-free emulsion polymerization, no chemical initiator and emulsifier, a copolymer latexes of BA (butyl acrylate)/St (styrene)/AM (acrylamide) was prepared. The influence of ultrasonic time on monomer conversion, latex particles size and latex viscosity was investigated. A polymerization mechanism of ultrasonic emulsifier-free emulsion polymerization also was proposed, which indicated that AM was as an initiator and stabilizer in the reaction system. TEM photographs showed that the size of latex particles was about 80 nm, which was less than that (about 140 nm) of the particles prepared by conventional emuilsifier-free emulsion polymerization method. And FTIR spectrum showed that after extracted in turn by water, CCl3 and THF for 48h, respectively, the sample obtained by this way was a ternary copolymer of BA, St and AM, but not the blend of poly(butyl acrylate), polystyrene and polyacrylamide.