MMA-EA-DM三元共聚胶乳的制备及共聚物表征

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

以 (NH4 ) 2 S2 O8 Na2 SO3为氧化还原引发体系 ,于 45～ 60℃ ,进行MMA -EA -DM三元乳液共聚合 ,比较两种聚合方法 ,得出采用无种子半连续乳液聚合法所得乳液稳定性好 ,其转化率为 99% ,共聚物的特性粘数为 412ml/g ,并对共聚物进行了IR、1 HNMR的研究 ,结果表明 :三元乳液共聚合时 ,基本上合成的是三元共聚物 ,其组成为n(DM ) /n(MMA) /n(EA) =0 75 /1/1,由于单体DM溶于水 ,有极少量的DM均聚物或富集DM的共聚物生成 ,其摩尔分数为 3 6%。

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.