Functionalization of fluoropolymer surfaces with nanopatterned polyelectrolyte brushes

We present a strategy to combine the excellent bulk properties of fluoropolymer substrates with the wide range of functionalities of surface-grafted polyelectrolyte brushes. Patterns of radicals serving as initiators were created by irradiation with extreme ultraviolet light (EUV) in an interference setup at the Swiss Light Source. From these initiators, brushes of poly(methacrylic acid) or poly(4-vinylpyridine) were grafted in one step by free-radical polymerization. Brushes carrying primary or secondary amines, i.e. poly(vinylamine), poly(allylamine) and poly(N-methyl-vinylamine), were obtained by grafting vinylformamide and acrylonitrile followed by hydrolysis or reduction. Periodic patterns with a resolution of 200 nm were achieved, while the thickness of the brushes in unpatterned areas could be controlled over a range of several hundred nanometers by variation of EUV dose and grafting parameters. The maximum dry brush thickness was used to estimate the average molecular weight of the polymer chains.