In this study, inverse emulsion polymerization (IEP) of acrylamide (AAm) and 2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS) was conducted with a constant monomer AAm/AMPS feed ratio of 80%:20%. The effects of important reaction parameters on monomer conversion, intrinsic viscosity and molecular weight of nanostructured polymers (NSPs) were comprehensively assessed and the optimal synthesis conditions (in terms of the high molecular weight characteristics) was obtained using Box–Behnken design (BBD) combined with response surface methodology (RSM). The glass transition temperature (Tg) of the synthesized NSP was obtained at 165 °C by differential scanning calorimetry (DSC). The rheology measurements demonstrated the long–term stability of the synthetized NSPs after 50 days of aging at 90 °C within the 87,000 ppm brine. Regarding the high molecular weight and acceptable long–term stability at elevated temperatures and salinity levels, the synthesized NSP could be considered as potential candidates for enhanced oil recovery (EOR) applications under harsh condition reservoirs
