Spontaneous Imbibition of Bicontinuous Microemulsions into Hydrophilic and Hydrophobic Controlled Pore Glasses

The effects of hard confinement are of great importance for many applications and also from a scientific point of view. These effects include a reduction in degrees of freedom and changes in phase behavior, structure, and molecular interactions. Simple and complex fluids can enter and occupy a porous matrix by imbibition. In this work, the results of an investigation into the spontaneous imbibition of bicontinuous microemulsions, serving as a model system for a complex fluid, into columns of granular, controlled pore glasses (CPG) are reported. The spontaneous imbibition of 1-octanol, a simple fluid with viscosity and surface tension similar to the bicontinuous microemulsion, is investigated for comparison. Controlled pore glasses with three different pore diameters between 11 and 112 nm with hydrophilic and hydrophobic surfaces are chosen. Two imbibition regimes were observed for the three investigated controlled porous glasses. Comparatively fast imbibition occurs due to the presence of voids between the individual CPG grains, while the uptake of liquids into the actual pores is much slower.