Oxford, England – A groundbreaking study conducted by scientists at the University of Oxford challenges a fundamental principle of physics. The research, published in the journal Nature Nanotechnology, reveals that similarly charged particles in a solution can attract each other over long distances, a phenomenon that varies depending on the type of solvent present.
The team of researchers from Oxford’s Department of Chemistry discovered that negatively charged particles tend to attract each other at large separations, while positively charged particles repel each other. This effect was found to be influenced by the nature of the solvent, with different behaviors observed in solvents such as water and alcohols.
In a surprising twist, the study found that the rule of “like charges repel; opposite charges attract” does not always hold true when considering the impact of the solvent on interparticle interactions. This finding has significant implications for various scientific processes, including self-assembly, crystallization, and phase separation.
Using bright-field microscopy, the researchers observed that negatively charged silica microparticles formed hexagonally arranged clusters in water, while positively charged particles did not exhibit this behavior. The team proposed a theory of interparticle interactions based on solvent structure at the interface to explain these observations.
Further experiments revealed that the ability of charged particles to form clusters was pH-dependent, suggesting that the formation of clusters could be controlled by adjusting the pH of the solution. Additionally, changing the solvent to alcohols resulted in a reversal of the clustering behavior, with positively charged particles forming clusters while negatively charged particles did not.
Professor Madhavi Krishnan, who led the study, expressed pride in the collaborative effort of her team, highlighting the significant impact of the discovery on our understanding of interparticle interactions. The findings open up new possibilities for studying the properties of interfacial electrical potential due to the solvent in ways that were previously thought impossible.
The study signifies a shift in our understanding of fundamental principles in physics and chemistry, with far-reaching implications for various scientific and industrial applications. The researchers hope that their work will inspire further exploration into the role of solvents in influencing intermolecular interactions and transformative processes.