Chen and Wang in Caltech found water entropy drives charged polymers assembly in water

What is it about?

By exploiting the temperature dependence in the dielectric constant of water, we show that, for systems with weak and intermediate electrostatic strength, the main driving force for both the polycation–polyanion complexation and the subsequent coacervation, arises from the entropy associated with the solvent degrees of freedom, thus highlighting the importance of solvent reorganization for ionic interactions in aqueous solutions (and in polar solvent in general) of electrolytes and polyelectrolytes.

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Why is it important?

The work resolves a major discrepancy regarding the thermodynamic driving force for polyelectrolyte coacervation, and shows that at least in the regime of weak and intermediate electrostatic strength (which covers a broad range of experimental systems), it is the solvent reorganization entropy, not the counterion-release entropy (as is commonly believed), that drives the electrostatic assembly.