Water-based preparation of highly oleophobic thin films through aggregation of nanoparticles using layer-by-layer treatment

The layer-by-layer (LBL) adsorption technique has potential for controlling the surface wettability. In this study, we controlled surface wettability between "superhydrophobic and oleophobic" and "hydrophobic and oleophilic" by LBL process on TiO ₂ nanoparticle with hydrophobic polymer and hydrophilic polymer. From the cast coating with LBL process on TiO ₂ nanoparticle, the surface showed "superhydophobic and oleophobic" when the top surface was hydrophobic polymer, on the other hand, the surface showed "hydrophobic and oleophilic" when the top surface was hydrophilic polymer. The LBL process also affected to the structure of TiO ² nanoparticle/polymer composite, and TiO ₂ nanoparticle were aggregated with polymers in LBL process. In the condition of the aggregated diameter of TiO ₂ nanoparticle/polymer composite around 10 μm in solution, the oleohobicity of spray coated film was enhanced with its hierarchical structure (static contact angles of rapeseed oil of 150° and hexadecane of 145°) "Superhydrophobic and high oleophobic" surfaces generated from all water-based dispersions are expected for application in technologies that need to avoid organic solvents.