Reduction of the hydrophobic attraction between charged solutes in water

TL;DR

This study uses Molecular Dynamics simulations to investigate how charging nanometer-scale solutes in water affects hydrophobic attraction, revealing surprising behaviors including like-charge attraction.

Contribution

It demonstrates, through simulations, that charging reduces hydrophobic attraction and uncovers phenomena like like-charge attraction at contact.

Findings

Effective force remains constant for oppositely charged solutes at contact.

Like-charged solutes show different behaviors, with positive and negative pairs diverging.

Confirmation of like-charge attraction in colloidal dispersions.

Abstract

We examine the effective force between two nanometer scale solutes in water by Molecular Dynamics simulations. Macroscopic considerations predict a strong reduction of the hydrophobic attraction between solutes when the latter are charged. This is confirmed by the simulations which point to a surprising constancy of the effective force between oppositely charged solutes at contact, while like charged solutes lead to significantly different behavior between positive and negative pairs. The latter exhibit the phenomenon of ``like-charge attraction" previously observed in some colloidal dispersions.