That's not necessarily the case, according to a new study published in Did you know how similarly charged objects repel, and they do so regardless of the sign of their charges? Nature.
“We have experimentally shown that the solvent plays a previously unexpected but important role in particle-particle interactions,” they write. But more importantly, “interactions in the liquid phase can break the symmetry of charge reversal.
We found that in aqueous solutions, negatively charged particles are attracted over long distances, while positively charged particles are repelled. [In solvents like alcohols “that exhibit an inversion of the net molecular dipole at an interface”]positively charged particles can be attracted, while negatively charged particles are repelled.
This observation holds true across a variety of surface chemistries, from inorganic silica and polymer particles to surfaces coated with polyelectrolytes and polypeptides in aqueous solutions.
The theory of interparticle interactions leading to structuring of the solvent at the interface provides the observed results. Our work establishes a nanoscale interfacial mechanism in which solvent molecules generate strong and long-range forces in solution, allowing them to interact with a variety of particles across length scales, including self-assembly, gelation and crystallization, and biomolecules. and have an immediate effect on molecular processes. Condensation, coacervation, phase separation.
Subtle interactions between objects in the fluid phase influence the behavior, composition, and properties of systems ranging from nanometers to more macroscopic size and length scales, thereby supporting a wealth of natural phenomena. I'm…
Thanks to longtime Slashdot reader Greymane for sharing the article.