Aqueous two-phase polymerization is that the water-soluble monomers are dissolved in the aqueous solution of another water-soluble polymer and polymerize to form an immiscible aqueous two-phase system of polymer solutions. The advantages of the aqueous two-phase polymerization are the lower viscosity and higher monomer concentration of the polymerization system, and such method overcomes the problems of agitation and heat release in homogenous aqueous polymerization. The phase diagram of the PAAm-PEG-H2O aqueous two-phase system was measured by turbidimetry titration. The phase separation was found to occur more easily when the temperature was about 55 degrees C The micrograph of the product prepared by the aqueous two-phase polymerization showed that the poly(acrylamide) (PAAm) rich aqueous solution dispersed in the continuous poly(ethylene glycol) (PEG) rich aqueous solution phase as a droplet phase. As the polymerization proceeded, the viscosity of the system increased gradually, the final viscosity of the aqueous two-phase polymerization system was about 1.7 Pa (.) s, and far lower than that of homogeneous aqueous polymerization system. The viscosity variation with the concentrations of acrylamide, initiator, PEG and emulsifier were investigated. The viscosity of the aqueous two-phase polymerization system increased with increasing of PEG concentration. When the monomer concentration exceeded 1.5 mol/L, the viscosity of the aqueous two-phase polymerization system increased sharply. The initiator concentration showed a little effects on the viscosity of the aqueous two-phase polymerization system. When high emulsifier concentration was used, the viscosity of the aqueous two-phase polymerization system increased sharply. As the polymerization temperature rose, the viscosity of the aqueous two-phase polymerization system decreased at first then increased, it coincided with the results of the phase diagram.
