Unraveling the Hydration Behavior of Poly(2-Methoxyethyl Acrylate) and Its Model Monomer via Molecular Dynamics Simulations.

The hydration behavior of polymeric materials is governed by a subtle interplay between local chemical functionality and polymer backbone connectivity. In this work, we investigate the hydration behavior of poly(2-methoxyethyl acrylate) (PMEA) and its monomeric analogue, 2-methoxyethyl acetate (MEA), using molecular dynamics simulations. MEA is examined at infinite dilution and at water contents ranging from 40 to 9 wt %, and the hydration behavior across this hydration range is compared with that of PMEA at 9 wt % water to assess the degree of similarity and to isolate the role of the collective effects associated with the polymer architecture. Hydration behavior is analyzed using a range of structural and dynamical metrics. Structural analyses reveal that at 9 wt % water, MEA and PMEA exhibit similar local hydration structures around their various oxygen sites, indicating comparable short-range coordination. In contrast, dynamical properties show pronounced differences: water in PMEA displays significantly slower translational motion, longer residence times near polymer oxygen sites, and markedly prolonged hydrogen-bond dynamics compared to MEA at the same hydration level. The results demonstrate that, despite similar local hydration structures, the polymer architecture imposes strong dynamical constraints on interfacial water, resulting in a clear decoupling between local hydration structure and interfacial water dynamics. The study provides molecular-level insight into the distinctive hydration behavior of PMEA and highlights the importance of considering hydration dynamics alongside local hydration structure.