Behavior of Water and Ions Within Polyethylene: Insights from Molecular Dynamics Simulations

Understanding the molecular-level behavior of water and ions is crucial for comprehending the degradation phenomena in polymeric materials. This study employs molecular dynamics simulations to investigate the behavior of water, sodium ions (Na+), and sulfate ions (SO42-) within alkane molecules (C120H242). Our approach involved constructing various computational models to simulate the dynamics of water and ions under electric fields, particularly on their behavior within spaces confined by C120H242. The findings reveal significant insights: in free water, electric fields significantly influence the diffusion constants of Na+ and SO42-. A notable observation is the reduced mobility resulting from increased attraction between Na+ and SO42 in the absence of water. In confined spaces, diffusion becomes more pronounced when ion movement aligns with the direction of electric field, and a lower concentration of ions correlates with higher diffusion constants. Moreover, under intense electric fields, ions and water molecules are observed to penetrate C120H242, thereby maintaining an ordered arrangement.