The drying process is similar to that of a sessile drop but, the surface tension is not uniform at the evaporating inner meniscus edges. This leads to extra strain in the particle film at these areas which finally appears as cracks in a dried drop. Similar phenomena is observed in case of drying of gelatin droplets6.
Liu investigated the electrical conductivity of dried thin films of ellipsoids and found that the conductivity increases along with the decrease in the surface area in the film. In view of this, our materials engineer team is developing ellipsoidal particles with electrically conductive polymer coating (silver colloid).
We tested the performance of Film impacts by adding volume controlled anti-solvent to drop of food colored ellipsoid dispersions. A graduated test-tube was used to measure the initial volume of the drop in the presence of anti-solvent to test the film re-swell ratio (See Fig. 1). In the presence of anti-solvent a clear re-swelling of the film is observed with a systematic pattern. The re-swelling ratio depends on the initial volume of drop. The effectiveness of Film impact on film re-swelling can be demonstrated by measuring the speed of the film re-swelling. The measurements indicate that Film impact is capable of film re-swelling within one minute for an initial film volume of 220 μl. The average time for film re-swelling is less than 2-minutes using Film impact whereas it is more than 20-minutes by gelling the dispersion and draining the drop. The data suggest that Film impact is effective to induce the re-swelling of the porous solid particle films, which can be further used for a precise tuning of the film shape or volume after the particle coating is developed.
Optical growth of crystals in closed system is an important process in several applications. In our study, transition of isotropic initial dispersion of spherical colloids into ordered structure of layered particles is investigated using a simple closed system. The evolution of stable cluster phases in solution of spherical particles with different aspect ratios has been investigated by measuring the light scattering of the solute accurately. d2c66b5586