The aqueous two-phase copolymerization of acrylamide(AM) and methacryloyloxyethyl trimethyl ammonium chloride(DMC) with the initiator 2

2’-azobis[2-(2-imidazolin-2-yl)propane]-dihydrochloride in aqueous poly(ethylene glycol)(PEG) solution was studied. In order to determine the phase separation point where the transmittance declined suddenly

the spectrophotometer was employed to detect the transmittance of the reaction solution on-line. The effect of various parameters on the critical conversion of the reaction solution with total mass 50.0g was measured by improved bromating method. The critical conversion kept at about 37~38% as the initiator amount increased from 0.005g to 0.025g and the temperature increased from 45℃ to 65℃. And it decreased sharply as the monomers amount increased from 2.5g to 12.5g

decreased little with PEG amount increased from 2.5g to 12.5g

and also decreased with PEG molecular weight increased from 600 to 20000. But it increased with the mole fraction of DMC increased from zero to 20%. The critical molecular weight was also investigated by gel permeation chromatogram(GPC). When the initiator amount increased or temperature rose

the critical molecular weight both decreased linearly. When the overall monomers amount or PEG amount increased

the critical molecular weight increased firstly

and then decreased. The highest critical molecular weight was 3.64×105 and 7.59×105

respectively. As the mole fraction of DMC increased

the critical molecular weight decreased linearly. But when PEG molecular weight increased

it increased accordingly. The results showed that the effects of PEG molecular weight and mole fraction of DMC were most remarkable

the effects of overall monomers amount and PEG amount were little smaller

and the effects of initiator amount and temperature were smallest. Therefore

in order to bring about effective phase separation of the aqueous two-phase copolymerization system

the reaction parameters should be controlled in the suitable range. That is

initiator amount 0.005~0.025g

temperature 45~65℃

overall monomers amount 5.0~12.5g

PEG amount 7.5~12.5g

PEG molecular weight 10000~20000

mole fraction of DMC 5~10%

respectively.