The drying of latex suspensions is an out of equilibrium process during which gradients of concentration of species in suspension (both latex particules but also surfactants and other additives) develop. These gradients may alter the final properties of the film, such as its adhesion to the substrate, its mechanical strength or its optical surface aspect. We have developed a numerical tool, based on a cellular automata approach, that takes into account the currents of all species at play during drying in order to describe the evolution of the local concentration of the paint during drying. In particular, we have observed that the surfactant may accumulate at the air/latex or, oppositely, at the substrate interface, depending on the evaporation rate.
A. Gromer, M. Nassar, P. Hébraud, and Y. Holl. Simulation of Latex Film Formation Using a Cell Model in Real Space: Vertical Drying. Langmuir, 31 (40), 2015