Study On RAFT Dispersion Polymerization Of Acrylamide In Ethanol/Water Media

Acrylamide polymers have been widely used in the fields of sewage disposal,papermaking,oil recovery and textile because of the characteristics for thickening,flocculating and strengthening fiber toughness.On the basis of related studies,the water-soluble macro-CTA PMAA was used as the RAFT agent to control the dispersion polymerization of AM in ethanol/water mixed solution.Because the segment of PMAA-chain is water soluble and plays a role of dispersing and stabilization effects,a stable dispersion system can be obtained.At present,the research on RAFT dispersion polymerization is mainly focused on the preparation of amphiphilic block copolymers,and there are few reports about the preparation of double hydrophilic copolymers through RAFT dispersion polymerization.Based on the related researches,the RAFT dispersion polymerization of acrylamide(AM)and the swelling property of polymer were systematically discussed.The thermal stability,glass transition temperature and other properties of the polymerized products were also studied.In this thesis,s,s'-Bis(?,?'-dimethyl-?''-acetic acid)-trithiocarbonate(BDMAT)was selected as the RAFT reagent,methacrylic acid(MAA)as the main monomer,water-soluble azo-compounds 2,2'-Azobis(2-methylpropionamide)dihydrochloride(V-50)as the initiator,to prepare a series of macromolecular RAFT agent PMAA macro-CTA by aqueous solution polymerization.The RAFT dispersion polymerization of AM was regulated by PMAA macro-CTA in the mixture of ethanol and water.By orthogonal experiment,the optimum reaction conditions were determined as follows: molar ratios of AM/macro-CTA PMAA/V-50 was 6000/5/1,reaction temperature 50 ? and the mass ratio of ethanol to water 7/3.The polymerized products were characterized by FTIR,NMR,TEM,DLS,Zeta potential,viscometer,TGA and DSC.The results of thermogravimetric analysis showed that the order of thermal stability was PMAA-PAM-PMAA > PAM > PMAA macro-CTA.The results of DSC showed that the RAFT dispersion polymerization product of AM was the copolymer of AM and PMAA macro-CTA.By means of rotating viscometer and TEM,the swelling property of dispersion was systematically studied.The influences of composition of diluent,the speed of the viscometer and the solid content of the system on the apparent viscosity of dispersion system during the swelling process were investigated.The results showed that the macroscopic morphology and apparent viscosity of the samples were greatly influenced by the mass ratio of ethanol/water in the diluent.