Phase Separation And Droplet Formation Mechanism Of Aqueous Two-Phase Copolymerization Without Extra Stabilizer

Aqueous two-phase copolymerization(ATPP)of acrylamide(AM),2-methylacryloylxyethyl trimethylammonium chloride(DMC)and acryloyloxyethyl dimethylbenzyl ammonium chloride(AODBAC)using 2,2'-azobis[2-(2-imidazolin-2-yl)propane]-dihydrochloride or potassium persulfate(KPS)/Na2SO4 as initiators without extra stabilizer in aqueous solution were prepared.This dispersion does not contain any stabilizer or inorganic salts,and has low cost of production.Besides,it has high solid content.So it can be applied in industrial fields,such as water recycle in paper industry,wastewater treatment in dye industry and building industry.Specially,it can be used in some fields which inorganic salts and stabilizer are forbidden,such as cosmetic industry and so on.This way,the application fields of cationic polymer dispersion will be expanded.Spectrophotometer was used to record the change of the transmittance of ATPP solution without extra stabilizer on-line,and to detect the critical point of the phase separation.The critical conversion of the reaction solution was measured by improved bromating method.The critical molecular weight was measured by viscometric method.The effects of various parameters on the critical conversion and molecular weight were investigated.AODBAC was found to have a good performance on promoting phase separation of the system,and screening effect of an anionic comonomer and the copolymer concentration have a good performance as well.Change of the initiator amount and the mole fraction of quaternary ammonium cationic monomer have a little effect on the critical conversion.When temperature rose,the critical conversion increased.When the overall monomers concentration and the mole fraction of AM increased,the critical conversion decreased.When initiator amount,temperature,the mole fraction of AODBAC increased,the critical molecular weight decreased.When the mole fraction of AM and the overall monomers amount increased,the critical molecular weight increased significantly.In the end,a series of reaction conditions was proposed to prepare the stable ATPP dispersion without extra stabilizer.In order to investigate the droplet formation mechanism and stabilization mechanism of ATPP without extra stabilizer further.The self-assembling behavior of AODBAC polymer and polyacrylamide were studied.TEM was used to characterize the morphology of the assembly performance of AODBAC polymer.The change of copolymer composition during ATPP of DMC and AODBAC was determined.It was found that AODBAC tends to react with itself,and copolymer composition(FAODBAC)increased during the polymerization.The critical aggregation concentration(CAC)of the copolymer decreased with the reaction.Specially,the reaction rate of AODBAC increased fast when phase separation began.So,it can be found that AODBAC have a good performance on promoting phase separation of the system.The viscosity of the ATPP system during polymerization and the intrinsic viscosity of copolymer were measured.AODBAC was found to have a good performance not only on promoting phase separation,but also on decreasing the viscosity of the system.The effects of inorganic salt on the phase separation in the ATPP of DMC and AODBAC were studied,inorganic salts have a good performance on phase separation in some degree,and the results will help the controlling of ATPP system.Combined with copolymer composition,droplet morphology,zeta potential of ATPP system of DMC and AODBAC,the droplet formation and stabilization mechanism of ATPP without extra stabilizer was proposed.The droplet formation mechanism was association-growth-aggregation-growth.Stabilization mechanism concludes:electrostatic repulsion between polyelectrolyte,stabilizing effects of AODBAC,stabilizing effects of high molecular weight polyelectrolyte,synergistic effects of the polymer concentration.