Fig. 3. Interfacial behavior of particles during the drying of dispersions.

a–d Comparison between pure spherical PS particles (top), spherical (middle) and elliptical (bottom) PS particles with a physisorbed PVA layer (molecular weight: 130 kD). a, b Optical microscopy images of the contact line at the beginning (a) and towards the end (b) of the drying process. c Interparticle distance distribution at the start (blue) and towards the end of the drying process (black). The dotted line represents the particle diameter (sphere) and width of the ellipsoidal particles respectively without PVA. d Schematic illustration of the interfacial morphology of the three particl typess as side view, top view and their assembly at the contact line during the drying of the dispersion droplet. e Drop weight as a function of time during the evaporation process. f Number of adsorbed particles per area (12,500 µm²) as a function of time for the three particle systems as well as for spherical particles with a shell consisting of 60 kD PVA and a spherical particle dispersion as without the removal of excess PVA. Scale bar: 20 µm.