Capillary bridge formation at room temperature in binary liquids with small miscibility

Abstract

Capillary suspensions, solid-liquid-liquid systems, are conventionally formulated by dispersing the particles in the bulk phase and then adding a small amount of secondary liquid (<5 vol%), leading to increased yield stress. Previous work has shown that partially miscible liquids form capillary bridges between particles upon temperature induced phase separation. In this work, we show that capillary suspensions can be formed by mixing particles with partially saturated 1-alkanol (6–8 carbon atoms)/water solutions, without the need for a temperature induced phase separation. Moreover, we show this effect works with different particle sizes and geometries. In addition, we illustrate that a pure suspension formed with 1-alkanols can create capillary suspensions when stored in humid conditions. This paper also demonstrates how partially miscible oil suspensions form capillary bridges even during the drying process when exposed to high humidity. This can lead to a significant decrease in drying stresses but also a change in structure.