Preparation of MMA-EA-DM Latex and Characterization of Copolymer

Methyl methacrylate(MMA)-ethyl acrylate(EA)-dimethylamineethyl methacrylate(DM) terpolymer emulsion was prepared by emulsion polymerization using a redox initiation system of (NH 4) 2S 2O 8 and Na 2SO 3,at 45～65 ℃ for 6～8 h.On comparing the two polymerization methods,the stability of the latex prepared by seed-free semicontinuous emulsion polymerization is better than that of the latex prepared by seed emulsion polymerization.The average particle size was approximately 100 nm.The intrinsic viscosity was 412 ml/g. The product's pH value fell within the range of 8 to 9.The purified polymer was characterized by IR, 1H NMR,and was found to be a terpolymer with a composition of 1∶1∶0 75(mole),with a small amount (about 3 6%(mol))of DM(or rich DM) copolymer.The nucleation mechanism of the emulsion polymerization system is micellar nucleation and homogeneous nucleation mechanism. TEM photographic studies showed that the latex particles were formed mainly by homogeneous nucleation due to the water solubility of DM monomer.