Fabrication of uniform thick films through dip-coating with vibration

Abstract

We study the fabrication of uniform thick polymeric films based on the dip-coating with vibration. In conventional dip coatings established by the Landau-Levich-Derjaguin theory, the fast process generates a coating thickness gradient while the slow process limits the film thickness and is time-consuming. Recently, fabrication method of thick films was proposed based on the dipping of a solid substrate in a neutral buoyancy bi-layer liquid bath and applying vibration. The film thickness is tailorable by varying the vibration frequency and amplitude. We conduct systematic experiments to analyze the physical ingredients that affect coating thickness. We find the inverse proportional relationship between the applied mechanical energy during an oscillation and the final coating thickness that is independent of an initial coating shape determined by the dipping rate. We also find that the viscosity has a little influence on the coating thickness while the density increase of the supporting liquid for neutral buoyancy formation reduces the coating thickness. Our results can be used to efficiently fabricate Functionally Graded Material.