Full Investigation of Angle Dependence in Dip-Coating Sol-Gel Films.

Dip-coating is one of the most convenient methods used in laboratory and industry to deposit a solid layer onto a surface with a controlled thickness from a chemical solution. The present Article investigates the influence of the withdrawal speed on the film thickness and homogeneity with respect to the dipping angle ranging from 90° (conventional vertical configuration) to 1° (quasi-horizontal configuration). Several advantages were found in the latter extreme low-dipping angle conditions that are (i) an available wider range of thickness, (ii) the elimination of the perturbations/effects induced by evaporation, and (iii) the compatibility with large surface and single face deposition at high throughput and using a minimal amount of solution. One shows that experimental data follow the Landau-Levich model, modified by Tallmadge for angle dependence, only for intermediate regimes of speed. A maximal thickness limited by the physical-chemical characteristics of the initial solution is reached at high speeds while a minimal thickness, corresponding to a single layer of solute interacting with the substrate surface can be obtained at very low speeds.