A novel water-soluble hydrophobically associating polyacrylamide based on oleic imidazoline and sulfonate for enhanced oil recoveryElectronic supplementary information (ESI) available: Synthesis routes, and their initial 1H NMR spectrogram analysis of NDS and NIMA; solution preparation and characterization; fluorescence spectra of different concentrations of copolymer solutions; the composition of synthesized brine for dissolving polymer particle samples in the rheological experiments. See DOI:

3-(2-(2-Heptadec-8-enyl-4,5-dihydro-imidazol-1-yl)ethylcarbamoyl)acrylic acid (NIMA), 3-(diallyl-amino)-2-hydroxypropyl sulfonate (NDS), acrylamide (AM) and acrylic acid (AA) were successfully utilized to prepare novel acrylamide-based copolymers (named AM/AA/NIMA and AM/AA/NDS/NIMA) which were functionalized by a combination of imidazoline derivative and/or sulfonate via redox free-radical polymerization. The two copolymers were characterized by infrared (IR) spectroscopy, 1 H nuclear magnetic resonance ( 1 H NMR), viscosimetry, pyrene fluorescence probe, thermogravimetry (TG) and differential thermogravimetry (DTG). As expected, the polymers exhibited excellent thickening property, shear stability (viscosity retention rate 5.02% and 7.65% at 1000 s −1 ) and salt-tolerance (10 000 mg L −1 NaCl: viscosity retention rate up to 17.1% and 10.2%) in comparison with similar concentration partially hydrolyzed polyacrylamide (HPAM). The temperature resistance of the AM/AA/NDS/NIMA solution was also remarkably improved and the viscosity retention rate reached 54.8% under 110 °C. According to the core flooding tests, oil recovery could be enhanced by up to 15.46% by 2000 mg L −1 of the AM/AA/NDS/NIMA brine solution at 80 °C. We report here a novel imidazoline functionalized hydrophobically associating copolymer that exhibits excellent rheological properties and outstanding potential for enhanced oil recovery.