Multilayer assemblies of poly(4-vinylpyridine) and poly(acrylic acid) bearing photoisomeric spironaphthoxazine via hydrogen bonding

The hydrogen bonding directed formation of a photochromic multilayer film was achieved on the basis of alternating assembly of poly(4-vinylpyridine) and poly(acrylic acid) bearing spironaphthoxazine. The assembling process was followed by UV-vis spectroscopy and X-ray diffraction measurement. Atomic force microscopy was used to investigate the surface morphology of the multilayer film, and the interaction between the two polymers was identified as hydrogen bonding through Fourier transform infrared spectroscopy. The resulting multilayer film presents photochromic properties through photochemical interconversation of spironaphthoxazine between closed-ring and colored open-ring forms. This method of alternately assembling polymers in an organic solvent via hydrogen bonding provides a solution to the problem of incorporating functional polymers with poor water solubility into a layer-by-layer self-assembled film.