Studies Of Reverse Atom Transfer Radical Polymerization For Acrylamide In Aqueous Two-Phase

Aqueous two-phase polymerization has relatively low viscosity and high concentration, and it does not have the pollution of organic solvent. So it has great practical value and wide applications in the future.Reverse atom transfer radical polymerization (R-ATRP) is derived on the basis of ATRP. R-ATRP overcomes many shortcomings of the conventional ATRP, such as the initiator is toxic, the low valence metal ions are difficult to preserve and easily to be oxidated.In this paper, Polyacrylamide (PAM) was synthesized by combining reverse atom transfer radical polymerization (R-ATRP) with aqueous two-phase polymerization. The controlled polymerization of acrylamide which using Fe(EDTA)2" and Cu(en)2+as initiator and control system respectively was discussed.Redox system consisting of potassium APS and Fe(EDTA)2-are used as initiator and control system in aqueous two-phase. The effect of AM concentration, the ratio of Fe(EDTA)2-and APS, the ratio of AM and PEG, reaction temperature and the ratio of Fe(Ⅱ) and EDTA was studied. The results indicate that the optimized conditions are as follows:PEG was used as dispersing agent and its mass concentration is10%, m(AM): m(PEG)=1:1, n(AM):n(APS)=2000:1, n(APS):n(Fe(EDTA)=2:1.5, n(Fe(Ⅱ)):n(EDTA)=1:2, and reaction temperature is55℃. Under these conditions the aqueous two-phase system shows the better stability and its phase separation in post treatment is easier, meanwhile, monomer conversion is94.1%, and the linear correlation coefficient is0.9931.In aqueous two-phase system, polyethylene glycol20000(PEG20000) is used as dispersing agent, potassium persulfate (KPS) and Cu(en)2+are used as initiator and control system, respectively. In this paper the effect of monomer concentration, the amount of Cu(en)2+, reaction temperature and the ratio of Cu(Ⅱ) and ethylenediamine (en) were investigated. The experimental result shows the optimum conditions are as follows: m(AM):m(PEG)=1:1, the monomer concentration is10%, n(AM):n(CuCl2·2H2O): n(en):n(KPS)=3000:10:20:1, and polymerization temperature is45℃. Under these conditions, the monomer conversion is91.5%, the linear correlation coefficient is0.9911.