Anomalous interactions in confined charge-stabilized colloid

TL;DR

This paper presents new thermodynamically consistent measurements confirming long-range attractions between like-charged colloidal spheres under confinement, supporting previous claims and providing insights into the underlying mechanism.

Contribution

It introduces a novel measurement approach that verifies anomalous colloidal attractions and sheds light on their possible origin.

Findings

Confirmed pairwise attractions in confined colloids

Supported previous experimental observations

Provided new insights into the attraction mechanism

Abstract

Charge-stabilized colloidal spheres dispersed in weak 1:1 electrolytes are supposed to repel each other. Consequently, experimental evidence for anomalous long-ranged like-charged attractions induced by geometric confinement inspired a burst of activity. This has largely subsided because of nagging doubts regarding the experiments' reliability and interpretation. We describe a new class of thermodynamically self-consistent colloidal interaction measurements that confirm the appearance of pairwise attractions among colloidal spheres confined by one or two bounding walls. In addition to supporting previous claims for this as-yet unexplained effect, these measurements also cast new light on its mechanism.