Process optimization of preparing honeycomb-patterned polystyrene films by breath figure method

Honeycomb-patterned polystyrene film is prepared by breath figure method. Pore size with a few hundred nano-meter to several micro-meter diameters is generated by controlling various parameters, such as the polymer concentration, humidity, casting area and solvent. The pore size becomes larger with increasing humidity and temperature difference between air and substrate. Porous film can be formed by drying under high humidity. The density of solvents affect the pore shape and pore depth. Video observation indicates that in the formation process of the porous pattern water droplet condenses gradually on the surface, along with the migration of the droplet formation boundary line from the edge to the center, when the boundary line reaches the center, hexagonally packed porous template is completed.