One-Step Process to Create Porous Structures in Cross-Linked Polymer Films Via Breath-Figure Formations During in Situ Crosslinking Reactions

We report a new strategy of fabricating honeycomb-like porous structures in cross-linked polymer films via a facile single-step synthesis/fabrication process. This is based on the breath figure (BF) formation during the in situ crosslinking of reactive monomer solutions. Applicable monomer solutions that have been found so far include (meth)acrylate and thiol-ene in various volatile solvents. Upon UV radiation under a moist and nitrogen saturated chamber, micron-sized pores with reasonable uniformity were obtained in the cross-linked polymer films. The size, shape, uniformity and ordering of the pores show significant dependences on the processing conditions. In particular, the pores at the peripheral regions appeared more uniform in size and showed higher degree of ordering, due to the interplay between the solvent evaporation and crosslinking reaction. Detailed characterizations of the chemical and physical properties, including the glass transition temperature, thermal stability, and surface wettability of the porous films were carried out.