Drying of colloidal droplets on hydrophobic surfaces

The evaporation of drops of colloidal suspensions on hydrophilic substrates leads to a variety of patterns, from the well-known coffee stain effect to radial crack formation. Here, we investigate the drying of aqueous solutions of silica nanoparticles on hydrophobic substrates for a large range of particle volume fractions. As the water evaporates, the particle volume fraction increases leading to a transition from a moving to a pinned contact line. This pinned contact line induces a large stress buildup within the material during the further evaporation process, which eventually gets released through the formation of fractures that shatter the dried drop into a multitude of pieces.