The copolymer (AP) of acrylamide

sodium acrylate

cetyl dimethyl ammonium chloride (C16DMAAC) and the copolymer (DP) of acrylamide

methacryloxyethyltrimethyl ammonium chloride and C16DMAAC were synthesized by the radical copolymerization.Then the AP and DP were characterized by infrared spectroscopy and 1H-NMR.At a constant NaCl concentration of 10000 mg/L

AP and DP were blended to form compound solutions to study the synergistic effect and mechanism between AP and DP with opposite charge by viscosity

rheology and fluorescent measurements.The viscosity measurements showed that the apparent viscosity of the compound solution (AP and DP quality ratio of 7 ∶3) was greatly higher than that of the mono-component polymer solutions with the same mass concentration which indicated that a significant effect was existed between the two polymers.The synergistic effect was stronger between AP and DP when pH=6~8.When the concentration of polymer was 2000 mg/L and concentration of NaCl was 15000 mg/L

the apparent viscosity of AP and DP was 19.9 mPa s and 4.2 mPa s

respectively

while the apparent viscosity of compound solution was up to 370.2 mPa s

which demonstrated a strong salt resistance.Comparing the plateau modulus (G0) and characteristic relaxation time (TR) of compound solution with those of the mono-component polymer solutions

it was proved that the number and structural strength of associations of compound solution were higher than those of the mono-component polymer ones.Additionally

comparing I3/I1 and Ie/Im of compound solution with those of the mono-component polymer solutions

it was also proved that the hydrophobic microdomain number of compound solution was higher than that of mono-component polymer solutions.