Superhydrophobic Barrier Films by Surface-Initiated Polymerization

摘要

The design of coatings that provide ultra-large resistances against the transport of water and ions has largely focused on the use of thick polymers of various compositions deposited by classical methods. Here, we show that ultrathin films of the world’s simplest and most common polymer, polymethylene (PM) (or the chemically equivalent polyethylene), exhibit dramatically large resistances against the penetration of aqueous ions if their topology is sufficiently rough on both micro- and nano-scales to merit superhydrophobic behavior. To achieve these rough, yet thin, PM films, we report a new surface- initiated polymerization strategy known as polymethylenation in which immobilized borane moieties serve as active centers for the reaction with diazomethane to grow PM chains one methylene group at a time from a variety of substrates, including gold and silicon.