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Multivalent Ion-Mediated Polyelectrolyte Association and Structure
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DOI：10.1021/acs.macromol.3c02437.png)
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Abstract
En 中文
Polyelectrolytes are commonly used to chelate multivalent ions in aqueous solutions, playing a critical role in water softening and the prevention of mineralization. At sufficient ionic strength, ion-mediated polyelectrolyte-polyelectrolyte interactions can precipitate polyelectrolyte-ion complexes, a phenomenon known as like-charge attraction. While the significant influence of small ions on polyelectrolyte solution phase behavior is recognized, the precise molecular mechanisms driving the counterintuitive phenomenon remain largely elusive. In this study, we employ all-atom molecular dynamics simulations to investigate the molecular mechanism of like-charge attraction between two poly(acrylic acid) (PAA) chains in solution. We find that moderate quantities of Ca2+ ions induce attraction between PAA chains, facilitated by the formation of PAA-Ca2+-PAA bridges and a significant increase in the coordination of Ca2+ ions by the PAA chains. At high Ca2+ number densities, ion bridges are disfavored due to electrostatic screening, yet the chains are still attracted to each other due to solvent-mediated interactions between the chains and their chelated ions. The insights gleaned from this study not only enrich our understanding of the intricate mechanism of like-charge attraction between polyanions in solution but also illuminate the influence of multivalent ions on polyelectrolyte interactions.
Keywords:
PROTEIN-PROTEIN INTERACTIONS
PARTICLE MESH EWALD
MOLECULAR-DYNAMICS
ANIONIC POLYELECTROLYTES
POLYACRYLATE CHAINS
REPLICA EXCHANGE
SOFTWARE NEWS
CALCIUM
SALT
ATTRACTION
Journal
IF:
5.2
Papers:
3.7W
Citations:
9.4W