Effect of the polydispersity of a colloidal drop on the drying induced stress as measured by the buckling of a floating sheet

摘要

We study the stress developed during the drying of a colloidal drop of silicananoparticles. In particular, we use the wrinkling instability of a thinfloating sheet to measure the net stress applied by the deposit on thesubstrate and we focus on the effect of the particle polydispersity. In thecase of a bidisperse suspension, we show that a small number of large particlessubstantially decreases the expected stress, which we interpret as theformation of lower hydrodynamic resistance paths in the porous material. Ascolloidal suspensions are usually polydisperse, we show for different averageparticle sizes that the stress is effectively dominated by the larger particlesof the distribution and not by the average particle size.