Controlling the buckling instability of drying droplets of suspensions through colloidal interactions

The present study focuses on the drying of droplets of colloidal suspensions using the Leidenfrost effect. At the end of drying, grains show different morphologies: cups or spheres depending on the ionic strength or zeta potential of the initial suspension. High ionic strengths and low absolute zeta potential values lead to spherical morphologies. A model based on the calculations of DLVO potentials has been implemented to extract a critical pressure, which provides a quantitative criterion for buckling whatever the initial formulation is. Particularly, the buckling time is quantitatively predicted from the interparticle interactions and shows an excellent agreement with experimental values. We show that the control of the interactions between colloidal particles determines the shape of dried millimeter sized suspension droplets, which can remain spherical or buckle.