Synthesis And Performance Analysis Of Polyacrylamide Surfactants With Long Carbon Chains

In this paper,diallyl alkylamines DC_nA（n=14,16,18）were synthesized by reacting diallylamine with bromoalkanes of different carbon chain lengths,and then the synthesized DC_nA were reacted with benzyl bromide to obtain the quaternary ammonium salts DC_nAB（n=14,16,18）,which were polymerizable surfactant monomers.The structures of DC_nAB were confirmed by their¹H NMR and FT-IR spectra.A series of ternary polyacrylamide surfactants PAMQ were obtained by copolymerization of AM,AMPS and DC_nAB via micelle polymerization.The structures of the polymer surfactant PAMQ were confirmed by their ¹H NMR and FT-IR spectra.After screened the polymerization conditions on the viscosity average molecular weight of PAMQ,the optimal reaction conditions were set up as follows:the monomer mass ratio of AM:AMPS:DC_nAB was 81:18:1,the p H value was 10.3,and the amount of SDS used was 4 times of the mass of DC_nAB,the amount of KPS used was 0.08%of the mass of the monomers,the amount of Na HSO₃ used was 0.05%of the mass of the monomers,the amount of AIBA used was 0.018%of the mass of the monomers,the initial reaction temperature was 25.0°C,and the amount of disodium EDTA used was 0.01%of the mass of AM.A series of ternary polyacrylamide surfactants PAMQ1～PAMQ3 were synthesized by micellar polymerization under the reaction conditions mentioned above,and their viscosity average molecular weights Mηwere 7.27×10⁶,8.94×10⁶and 7.12×10⁶ g·mol^-1,respectively.The TGA analysis showed that the polymer PAMQ had relatively high thermal stability,and the thermal weight loss temperature of the polymer backbone was 320°C.The polymers PAMQ1～PAMQ3 had good viscosity-increasing ability to the water phase.When the mass concentration of the polymer solution was 3.0 g/L,the shear rate was 7.34 s^-1 and the temperature was 25.0℃,the apparent viscosities of the solutions were 518.5,546.0 and 564.3 m Pa·s,respectively.Polymers PAMQ1～PAMQ3 had relatively good surface activities,the critical micelle concentrations（CMC）of copolymers PAMQ1～PAMQ3 were 2.14,1.94 and 1.78 g/L,respectively,and the corresponding critical surface tensions(γ_CMC)were 57.41,52.35 and 50.79 m N/m,respectively.Copolymers PAMQ had certain salt resistance and shear resistance properties.When the concentration of Na Cl was 200.0 g/L and the mass concentration of the polymer solution was 3.0 g/L,the apparent viscosities of copolymers PAMQ1～PAMQ3 solutions could be retained to 32.77,37.21 and 45.10m Pa·s,respectively.When shear rate was 200.0 s^-1 and the mass concentration of the polymer solution was 3.0 g/L,the viscosities of the polymer solutions were retained as 26.25,29.53 and33.85 m Pa·s,respectively.The emulsification and viscosity reduction performance of copolymers PAMQ for Liao He dehydrated heavy oil(apparent viscosity was 3184 m Pa·s at 25.0℃under shear rate of 7.34 s^-1)were studied.It was showed that copolymers PAMQ had certain emulsifying and viscosity reduction ability to Liao He dehydrated heavy oil and an O/W type emulsion was formed and the viscosity reduction rates were ranged from 78.2%to 85.7%.In order to further improve the emulsification performance of the polymer and the stability of the emulsion,the non-ionic polymerizable surfactant nonylphenol polyoxyethylene ether acrylate NP₃₀AA was introduced to the polymer and the quaternary polyacrylamide surfactants PAAQN1～PAAQN3 were synthesized via micelle polymerization under the reaction conditions mentioned above.After screening the amount of monomer NP₃₀AA used,the optimal recation racation condition was set up as follows:the monomer mass ratio AM:AMPS:DC_nAB:NP₃₀AA was 80:18:1:1,a series of quaternary polyacrylamide surfactants PAAQN1～PAAQN3 was synthesized and their structures were confirmed by FT-IR and ¹H NMR spectra.The properties of PAAQN1～PAAQN3 such as the thermal stability,the viscosity-increasing effect on water,the surface activity,the hydrophobic association,the wettability,the rheology,the emulsification performance of heavy oil and the stability of the emulsion were studied.The critical micelle concentrations（CMC）of PAAQN1～PAAQN3 were 2.05,1.89 and 1.76 g/L,respectively,and the corresponding critical surface tensions(γ_CMC)were 55.74,47.63,and 44.21 m N/m,respectively.Copolymers PAAQN1～PAAQN3 had a good emulsification and viscosity reduction ability to Liao He dehydrated heavy oil(apparent viscosity was 3184 m Pa·s at 25.0℃under shear rate of 7.34 s^-1)and an O/W type emulsion was formed.The viscosity reduction rates were 82.1%,87.6%and 91.4%,respectively.The emulsions were stable for more than 24 h.