Recently, polymer-modified bentonite-based GCLs have gained significant attention due to their superior hydraulic performance. When interacting with aggressive leachates, polymerized bentonites (PBs) showed a significantly lower hydraulic conductivity than sodium bentonites (NaB). From a microstructural perspective, researchers have put forward various underlying mechanisms for their enhanced hydraulic properties. However, the clay-polymer interaction corroborating their micro and macro behavior has not been thoroughly investigated. This could be potentially attributed to the variations brought about by the polymer type, dose, its properties, and the chemical nature of the permeant. Therefore, an endeavor to appraise the hydraulic behavior of PB through a systematic investigation of their fundamental properties is essential. Given this, for the first time, the present study attempted to investigate and discuss the physicochemical properties of PBs, which contain a wide range of polymer doses. PB was synthesized by polymerizing acrylic acid within NaB slurry. The physicochemical properties such as cation exchange capacity (CEC), bound cations, and zeta potential were evaluated experimentally. Further, the EGME and nitrogen gas adsorption techniques were used to measure the specific surface area of PB. The experimental observations revealed a significant change in the surface charge properties of clay, even with moderate polymerization. The increase in polymer load reduced the specific surface area of NaB, witnessing the polymer adsorption. Also, the polymer modification enhanced the ability to exchange cations with the surrounding pore fluid. Future research will characterize the above-discussed properties under various chemical environments to relate the microstructural changes and, hence, the macroscopic engineering properties.