Influence of vacuum on the formation of porous polymer films via water droplets templating

Abstract

We report on the formation of ordered arrays of micron-sized holes on the surface of polymer films cast from volatile solvents in the presence of humidity in vacuum. A lower pressure in a vacuum chamber can accelerate the evaporation of solvent in the same way as the accelerating action of the air flowing across the solvent surface and results in the formation of porous films via the “breath figure” templating method. This vacuum technique has a good reproductiveness for the fabrication of the well-ordered porous films in a large area. It is very controllable to prepare the porous films in a vacuum chamber via controlling the vacuum level. The pore sizes can be easily tuned from 5.6 to 17.1 μm by changing the vacuum level. The mechanism for the formation of the porous films in vacuum was also discussed. The polymer films with ordered porous structure and tunable pore sizes have potential applications in many areas such as microarrays and as scaffolds for tissue engineering.