Self-assembly in drying complex fluid at low capillary number

We study the pattern formation induced by drying colloidal suspensions and polymer solutions in a vertical Hele-Shaw cell immersed in a reservoir. The contact line speed is controlled by pumping out the solution from the reservoir. At low capillary number stick–slip motion of the receding contact line can be observed for silica suspensions. Periodic strips spontaneously form during drying. We study the strip periodicity and deposit morphology as a function of the receding velocity and pH of the solution. In the same conditions, dried polymer films are almost flat.

► We study the pattern formation induced by drying colloidal suspensions.
► The experimental setup is a dip-coating-like system with controlled evaporation rate.
► At very low capillary numbers periodic strips spontaneously form during drying.
► The deposit morphology depends on the receding velocity and pH of the solutions.
► In the same experimental conditions dried polymer films show only small ripples.