Halogen bonding as a new driving force for layer-by-layer assembly.

A new approach for fabricating a layer-by-layer polymer film was explored, which was based on the halogen bonding between poly(4-(4-iodo-2,3,5,6-tetrafluorophenoxy)-butyl acrylate) and poly(4-vinylpyridine). Layer-by-layer assembly of two polymers was confirmed by UV-vis spectroscopy and quartz crystal microbalance measurements. The interaction between the two polymers was identified as halogen bonding by X-ray photoelectron spectroscopy. The surface of the multilayer film is flat, and the thickness of one bilayer is about 1.3 nm. We also compared the stability of a halogen-bonded multilayer film in methanol with that of a hydrogen-bonded multilayer film.