The Synthesis Of Anionic Acrylamide-Polyelectrolyte By Precipitation Polymerization In Salt Solution

The synthesis of anionic acrylamide-polyelectrolytes by precipitation polymerization in salt solution is studied. Salt solution of precipitation polymerization of acrylamide is screened out and it is found that the capable salts include ammonium sulphate, potassium carbonate, ammonium citrate, potassium citrate and ammonium acetate. Typically select potassium citrate and ammonium sulphate to study the precipitation polymerization of anionic acrylamide in salt solution.The salt concentration of reaction system must be larger than the critical salt concentration of in precipitation polymerization and is limited by solubility of the salt. It is mensurated that the critical salt concentration of potassium citrate is from 32.10% to 61.90% as monomer ratio increase from 0 to 33%. The monomer concentration of reaction system is limited by the solubility of monomer in salt solution. And the solubility of monomer changes with monomer ratio. The conception of solubility parameter of salt solution is defined in order to expressing the solubility of monomer in the salt solution.Through single-factor experiment, the effect of monomer concentration, concentration of potassium citrate, polymerization time, stirring rate, initiator amount and monomer ratio on the weight, particle diameter, water content, salt content of precipitated colloid polymer, monomer conversion rate and salt content of the dried solid polymer is studied in solution of potassium citrate using (NH4)2S2O8-Na2SO3 as the initiator at 40℃. Then orthogonal array with the salt content of the precipitated colloid polymer is designed. Hereby the optimal reaction conditions is obtained: monomer concentration =1%, initiator concentration=800mg/L, polymerization time = 60min, medium salt concentration=42%, monomer ratio = 0, and stirring rate= 100r/min. The priority of the effects is: medium salt concentration, monomer ratio, stirring rate, initiator concentration, polymerization time, monomer concentration. Under the optimal reaction conditions the salt content of the precipitated colloid polymer is 26.78% which is less than thatof orthogonal array. And polyelectrolytes yield after purification by alcohol/water precipitation is 54.20%.Through single-factor experiment, the effect of monomer concentration, concentration of ammonium sulphate, polymerization time, stirring rate, initiator amount on the particle diameter, water content, salt content of precipitated colloid polymer and monomer conversion rate is studied in solution of ammonium sulphate using (NH4)2S2O8-Na2SO3 as the initiator at 40℃. Hereby the optimal reaction conditions is obtained: monomer concentration = 2%, initiator concentration = 800mg/L, polymerization time = 60min, medium salt concentration = 32%, stirring rate= 100r/min.