Molecular Dynamics Simulation: Tendency for CO₂ Adsorption in Amphiphilic Cellulose-Derived Interpenetrating Network Gels

The subject of CO₂ subsurface storage security has never been more critical, and there is a need to explore the injection of functional materials that are capable of providing both conformance control and in situ CO₂ adsorption, thereby improving overall formation storage integrity. Herein, a molecular dynamics simulation method was used to investigate the adsorptive tendency of two variants of interpenetrating network (IPN) composite materials comprising amine-stabilized hydrophobically modified cellulose sulphates and methylene bisacrylamide crosslinked polyacrylamide. Using the COMPASS III force field and Metropolis Monte Carlo, the diffusivity and adsorption isotherms for CO₂ were determined in the IPN gels, respectively. The results indicate that the two interpenetrating networks D-I-AM-MBA-G-Cl and D-II-AM-MBA-G-Cl demonstrated reasonable CO₂ adsorption. In saline conditions, the adsorption was further enhanced with diffusion coefficients of 4.87 × 10⁻⁴ cm²/s and 2 × 10⁻⁶ cm²/s. The adsorption isotherm of D-I-AM-MBA-G-Cl closely fits the Sips equation, with a regression coefficient of 0.9996, while that of D-II-AM-MBA-G-Cl follows the Temkin isotherm with an R² value of 0.9885. This study revealed that carefully designed plugging agents with strong CO₂ adsorption tendencies can aid in the improvement of the geosequestration integrity of subsurface formations.