Engineering repairable nanoporous functional coatings on arbitrary substrates by manipulating phase behaviors of block copolymers

Nanoporous polymers are extensively coated on various substrates to deliver optical, permselective, or other functions. However, it remains desired to fast produce uniform nanoporous polymer coatings on substrates with complex surfaces. Herein, by manipulating the interactions between block copolymers and selective solvents, we prepare repairable nanoporous polymers on arbitrary substrates. This is realized by an extremely simple sequential coating process: sequential coating of block copolymers and their swelling agents on substrate surfaces. The swelling agents are comprised of two solvents that swell the constituent blocks of the copolymers to different degrees, rapidly producing polymer coatings with uniform, interconnected, sub-50 nm pores. This sequential coating process is able to conformally build nanoporous polymers on nonplanar substrates with large lateral sizes and complex surface features, and also to in situ repair defects arising during usages. We further demonstrate that the nanoporous coatings show excellent antireflective and membrane separation performances. This sequential coating process is dictated by polymer–solvent interactions, and is expected to find applications in diverse fields for its simplicity, adaptability, and the capability to produce well-defined nanoporosities.