Wet nanogranular materials: colloidal glass and gel

Partially wet granular medium is a mouldable material due to capillary cohesion and its behavior plays key roles in geophysics. However, completely wet nanogranules may also demonstrate mouldable properties via van der Waals attraction and they exhibit colloidal glass or gel characteristics, depending on the solvent. As solvent-enhanced attractions prevail, phase separation is observed and nanogranular gel can be obtained. In contrast, as cage effects dominate, the stable slurry is seen and the nanogranular glass can be prepared. Upon surfactant addition, however, the arrested glass state changes into colloidal gel due to the formation of hydrogen bonds between nanogranules.