Preparation and Solution Characteristics of a Novel Hydrophobically Associating Terpolymer for Enhanced Oil Recovery

Hydrophobically associating terpolymers were prepared by the micellar copolymerization technique using acrylamide (AM), 2-trimethylammonium ethyl methacrylate chloride (TMAEMC) as a cationic monomer, and small amounts of 5,5,5-triphenyl-1-pentene (TP<0.5 mol-%) as the hydrophobe. The structure of the copolymer was characterized by FT-IR and ¹H-NMR. The aqueous solution properties of the terpolymers were also investigated as functions of polymer concentration, salinity, temperature and shear rate. The results showed that the thickening behavior of these terpolymers are remarkably dependent on both the number and length of hydrophobic segments in the copolymer chains. As expected, the terpolymers exhibited improved viscosity enhancement properties as the concentration exceeded 0.25 g⋅dL⁻¹, due to intermolecular hydrophobic association. Additional evidence for hydrophobic microdomains was obtained utilizing pyrene-probe fluorescence. Additionally, the ternary copolymers showed favorable salt tolerance, temperature resistance, and recoverable viscosity after shearing.