Patterning of hydrogen-bonded assembly film through ionization in vapor

The hydrogen-bonded films of poly(vinylpyrrolidone) (PVPON) and poly(acrylic acid) (PAA) were fabricated using layer-by-layer assembly technique. The films were incubated at three different vapor environments (acidic, neutral and basic). PAA would ionize in neutral or basic vapor environment, and then hydrogen bonds linking PVPON and PAA in the film would break and patterned topography would form gradually. Ionization degree of PAA in the film was characterized by Fourier transform infrared spectroscopy. Optical microscope and atomic force microscope were used to observe the film morphologies before and after incubation. Reflective spectroscopy and contact angle measurements were applied to further characterize the patterned surfaces.