CO2-triggered multiresponsive polymers for efficient gas channeling control: Conformational changes and dynamic network synergy

Multilevel CO 2 -responsive polymers with exceptional thickening performance. • SC-CO 2 triggered cationic transformation and high-temperature ion pair formation. • Synergistic coupling mechanism of chain conformational changes and dynamic networks. • SC-CO 2 induced an 8.3-fold viscosity increase of 0.5 wt% PAAHD within 10 min. • PAAHD demonstrated exceptional CO 2 -blocking efficacy, EOR was 18.56%. Existing CO 2 channeling-control strategies that rely on a single protonation-triggered mechanism to regulate polymer conformation through hydrophilic-hydrophobic microdomain evolution are often severely constrained under harsh reservoir. Therefore, breaking away from the conventional single-response paradigm, this study synthesizes a multilevel CO 2 -responsive polymer, PAAHD. In a supercritical CO 2 (SC-CO 2 ) conditions, the viscosity of a 0.5 wt% PAAHD solution sharply increased from 68.31 ± 2.10 mPa·s to 665.37 ± 18.40 mPa·s within 10 min. Even under a high mineralization of 10 × 10 4  mg/L, the system maintained a viscosity of 254.66 ± 7.60 mPa·s, far exceeding the previously reported value of 55.40 mPa·s. This significant viscosity enhancement originates from the synergistic construction of a protonation-induced dense hydrogen bonding network (with hydrogen bonding content increasing from 16.65% to 54.08%) and an ionic crosslinking physical network. Specifically, the reversal of Zeta potential from −10 mV to +24 mV, accompanied by an order-of-magnitude increase in electrical conductivity, indicates the transition of polymer chains to a positively charged state and a significant increase in ionic crosslinking density. This pronounced gelation transition is reflected in core displacement experiments as a 32-fold increase in injection pressure and an 18.56 ± 1.20% enhancement in oil recovery. This dual-mechanism synergistic responsive strategy provides an innovative solution for intelligent profile control. Download: Download high-res image (350KB) Download: Download full-size image