The utilization of traditional polymers like polyacrylamide in polymer EOR has revealed several challenges, such as a high surface absorption and a high sensitivity to the reservoir's salinity, as well as its thermal, mechanical, and bacterial properties. In this study, a novel core-shell nanostructure of polyacrylamide/polystyrene as protected polyacrylamide nanostructure (PPN) was prepared to overcome the aforementioned problems. A wide range of analytical techniques-such as IR, NMR, DSC, SEM, DLS, and SAXS-were used to examine the PPN structure, which confirmed a core-shell nanostructure with average with 61 nm core diameter and two shell thicknesses of 11 nm and 24 nm. Combined with rheology and release ability in the harsh environment, it was found that the PPNs show a time-dependent release behavior after contacting polymers to the hydrophobic phase. The results of mechanical- and temperaturedependent viscosities in presence of high total dissolved salinity (178,082 mg/L including divalent cations) illustrated viscosity of PPN samples increase with increased temperature and undergo a slightly reduction (2.37 %) with increased mechanical mixing. Besides, the adsorption analyses indicated that PPN samples adsorb weakly on silicate formations at all temperatures. All of this makes the PPNs a promising candidate for the polymer enhanced oil recovery.