Revealing the hidden dynamics of confined water in acrylate polymers: Insights from hydrogen-bond lifetime analysis

Polymers contain functional groups that participate in hydrogen bond (H-bond) with water molecules, establishing a robust H-bond network that influences bulk properties. This study utilized molecular dynamics (MD) simulations to examine the H-bonding dynamics of water molecules confined within three poly(meth)acrylates: poly(2-methoxyethyl acrylate) (PMEA), poly(2-hydroxyethyl methyl acrylate) (PHEMA), and poly(1-methoxymethyl acrylate) (PMC1A). Results showed that H-bonding dynamics significantly slowed as the water content decreased. Additionally, the diffusion of water molecules and its correlation with H-bond breakage were analyzed. Our findings suggest that when the H-bonds between water molecules and the methoxy oxygen of PMEA are disrupted, those water molecules persist in close proximity and do not diffuse on a picosecond timescale. In contrast, the water molecules H-bonded with the hydroxy oxygen of PHEMA and the methoxy oxygen of PMC1A diffuse concomitantly with the breakage of H-bonds. These results provide an in-depth understanding of the impact of polymer functional groups on H-bonding dynamics.

Automated summary

Polymers with functional groups can form hydrogen bonds with water molecules, which creates a strong H-bond network that affects their bulk properties. This study used molecular dynamics simulations to investigate the H-bonding dynamics of water molecules in three poly(meth)acrylates. The results showed that as the water content decreased, the H-bonding dynamics slowed down significantly. The diffusion of water molecules and its relationship with H-bond breakage were also analyzed. The findings suggest that the impact of polymer functional groups on H-bonding dynamics is dependent on the specific interactions between the water molecules and the polymer.