Role of Coating Thickness on Self-Stratification in Light-Curable Coatings

Abstract

This study investigates the effect of coating thickness on the self-stratification behavior of light-curable coatings composed of Gelatin Methacrylate (GelMA) and Acrylated Epoxidized Soybean Oil (AESO-GN). At a coating thickness of 30 μm, the structure is uniform without any phase separation. As the thickness increases to 60 μm and 85 μm, the morphology evolves into a self-stratified structure, with a combination of Type II and Type III classifications according to Funke’s classification. At 100 μm, a clear gradient-type self-stratified structure (Type II) is observed, with droplets migrating to the top of the coating. This transition is attributed to the increased bulk-to-surface ratio, where bulk forces gradually become more dominant over surface tension effects. The findings demonstrate that by varying the coating thickness, the self-stratification behavior can be precisely controlled. This provides an effective method for tailoring coating properties, such as mechanical strength, hydrophobicity, and durability, to meet specific application needs.