Patterns caused by buckle-driven delamination in desiccated colloidal gels

During desiccation of coatings, stress release results in mechanical instabilities that can occur in successive stages. Indeed cracks can divide a brittle coating into adjacent polygonal cells in response to important stress. We focus here on a later stage during which a delamination process is driven by buckling instability of the adjacent cells due to remanent stress in the layer. In this way we consider a drying colloidal gel in the geometry of a layer coating a substrate. This model system exhibits well-controlled physicochemical properties. We show that, in the final stage of the process, simple observation of partial delaminated cells allows for the determination of the adhesion energy of the system. Particularly, the influence of both the drying rate and the solvent on the process is experimentally studied.