Water and Carbon Dioxide in Hydrated Hyperbranched Polyethylenimine Membrane Using Molecular Dynamics Simulation and Density Functional Theory

Since excessive use of fossil fuels is releasing large amounts of CO₂ and exacerbating global warming, developing efficient materials to capture CO₂ is crucial. In this study, we investigate the hydrated hyperbranched polyethylenimine (HB-PEI) membrane in the presence/absence of water and carbon dioxide using molecular dynamics (MD) simulation to characterize their distribution and reaction mechanism in the HB-PEI membrane. For this, we prepare a model HB-PEI molecule and construct a condensed HB-PEI phase in the amorphous phase with various concentration of water and carbon dioxide molecules. Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) package is used in our MD simulations to establish the equilibrium state of HB-PEI membranes. Through our MD simulations, we obtain samples of the local structure of water/carbon dioxide nearby amine groups in HB-PEI membranes and scrutinize a possible molecular mechanism and corresponding energy barrier for carbon dioxide capturing, via density functional theory (DFT) approach.