Preparation of Poly(Sodium Acrylate) by Inverse Emulsion Polymerization

Poly (sodium acrylate) with high-molecular weight was synthesized with a redox initiator at 30～60 ℃ by inverse emulsion polymerization. The effects of reaction temperature, initiator concentration, molar ratio of oxidant to reductant, emulsifier concentration and weight ratio of compounding emulsifiers as well as acrylic acid neutralization on M w of poly(sodium acrylate) were studied. The results indicate the emulsification and stability of the reaction system are greatly influenced by the weight ratio of compounding emulsifiers and acrylic acid neutralization. The proper reaction temperature is 40～50 ℃. The proper reaction conditions are : initiator concentration , 4×10 -3 mol/L in water phase; molar ratio of oxidant to reductant, 2/1; emulsifier concentration, 5% by weight in total oil phase; hydrophile-lipophile balance(HLB) of compounding emulsifiers, less than 5.65 ; and acrylic acid neutralization, 70%.The M v of the obtained powdery poly (sodium acrylate) ranges from a few million to over ten millions, and the highest M v is up to 30 70 million.