Homogeneous deposition of particles on absorbing hydrogels
To realize a coating from a solution containing particles, the solvent has to be removed. Probably the most straightfoward method is drying. In other words, we can use evaporation that happens at the liquid-vapor interface. However, it exists another interface between the liquid and the substrate. If the substrate has absorbing properties, then this interface can be used to remove the solvent. We investigated this aspect with a model system consisting of a hydrogel prepared out of the swelling equilibrium. Then, we deposit a water droplet containing micron sized particles at the gel's surface. We observed that the final deposit has a remarquable homogeneity, contrary to a coffee drop. This observation may be used to functionalize surfaces of hydrogels, which receive a growing interest, especially for biotechnological applications.