Influence of mechanical properties of nanoparticles on macrocrack formation.

We present an experimental investigation of drying suspensions of both hard and soft nanolatex spheres. The crack formation is examined as a function of the proportion of hard and soft deformable particles, leading to tunable elastic properties of the drying film. In our experimental systems, no crack formation could be observed below an onset value of the proportion in hard spheres phi approximately 0.45 . During the drying process, the mass of films with various compositions in hard and soft spheres is measured as a function of time. The results suggest that the soft particles undergo deformation that releases the internal stresses.