In order to improve salt resistance

temperature tolerance and stability of the acrylamide-based copolymer

the hydrophobic associating copolymer (DTHAP) of acrylamide (AM) with acrylic acid (AA) and a double-tailed hydrophobic monomer (N-phenethyl-N-tetradecylmethacrylamide

PETMAM) was synthesized by photo-initiated radical polymerization. By measuring apparent viscosity of the hydrophobic associating polymer

the effects of amounts of acrylic acid

salt

surfactant (SDS) and content of the double-tailed hydrophobic monomer on the properties of the copolymer were investigated. The critical associating behavior of the copolymer could be affected by changing the amounts of surfactant and acrylic acid. Then

the amount of surfactant could be reduced by adding NaCl to the solution in the micellar polymerization process. Finally

even at low concentration [0.35%—0.45%(mol)] of hydropobic monomer

the copolymer could exhibit obvious thickness. For the hydrophobic associating copolymer synthesized

its critical association mass concentration was about 0.75 g·L-1 and its viscosity was 141.5 mPa·s at the concentration of 1 g·L-1. After ageing for 90 d at 80℃

the apparent viscosity of 2 g·L-1 DTHAP in 120 g·L-1 NaCl solution was 47.6 mPa·s. Even in 120 g·L-1 NaCl and 0.4 g·L-1 CaCl2 solution

the viscosity of the copolymer solution could be kept at around 45.9 mPa·s. The copolymer was characterized with FTIR and SEM

and its structure was confirmed.