Capillary suspensions: Particle networks formed through the capillary force

TL;DR

Capillary suspensions are materials where small amounts of secondary fluid induce particle network formation via capillary forces, significantly affecting their rheological properties and enabling new material design strategies.

Contribution

This review summarizes recent advances in understanding the mechanisms, properties, and applications of capillary suspensions, highlighting their potential for innovative material development.

Findings

Capillary forces induce particle bridging and network formation.

Capillary suspensions can be stabilized even when the secondary fluid wets particles less.

Applications include tuning rheological properties and designing new materials.

Abstract

The addition of small amounts of a secondary fluid to a suspension can, through the attractive capillary force, lead to particle bridging and network formation. The capillary bridging phenomenon can be used to stabilize particle suspensions and precisely tune their rheological properties. This effect can even occur when the secondary fluid wets the particles less well than the bulk fluid. These materials, so-called capillary suspensions, have been the subject of recent research studying the mechanism for network formation, the properties of these suspensions, and how the material properties can be modified. Recent work in colloidal clusters is summarized and the relationship to capillary suspensions is discussed. Capillary suspensions can also be used as a pathway for new material design and some of these applications are highlighted. Results obtained to date are summarized and central questions that remain to be answered are proposed in this review.