CHAPTER 7:Mechanical Instabilities Induced by the Drying of Complex Liquids

The drying of complex fluids such as polymer solutions and colloidal solutions is a challenging problem in soft matter physics that impacts a wide range of theoretical and applied situations. The drying phenomenon causes transport of nonvolatile components owing to hydrodynamic and diffusive flows. The consequent concentration of nonvolatile components at the interface results in the formation of a porous layer or skin that experiences large stresses, which subsequently result in mechanical instabilities that produce wrinkles or buckling. In addition, mechanical instability can result in the formation of cracks in the film as a consequence of differential shrinkage in a thick layer or adhesion to a substrate. In this chapter, we focus on these two kinds of mechanical instabilities that occur during the drying and consolidation of concentrated systems. Both model experimental systems and mathematical models to quantify measurements obtained during drying are discussed.