Fabrication of robust honeycomb patterned porous films by thermochemical cross-linking of polyimide

Robust honeycomb patterned porous (HCP) polymer films resistant to a wide range of organic solvents were obtained using polyimide (PI) by thermochemical cross-linking. For the robust PI HCP film, PI HCP film was fabricated via breath figure method, treated by aq. KOH to induce imide ring cleavage, and followed by reimidization using heat treatment at 120 degrees C. The robust PI HCP film was resistant to common organic solvents such as chloroform, etc. over than 20 h, while the pristine PI HCP film solubilized immediately. Morphology analyses of the robust PI HCP films showed good retention of HCP morphology without wreckage from the pristine films even after 20 h immersion in organic solvents. The film can be used as a robust template in soft lithography.