A new diol with a bisazoaromatic pendant was prepared to obtain photosensible polymers suitable for dyed aqueous systems. A polyurethane bearing bisazoaromatic chromophores, based on a poly(tetramethylene oxide) diol (average molecular weight = 2000), 2,4-tolylene diisocyanate, and the aforementioned azo diol, was synthesized and characterized. Bichromophoric polyurethane anionomers, prepared by a two-step substitution of urethane hydrogen atoms with sodium carboxylate groups, were studied. The influence of the concentration of carboxylate groups (30-158 mequiv of ionic groups/100 g of polymer) on some polymer properties and photoisomerism in polymer solutions and thin films was examined. In particular, the polymer structure and its morphology dictated the proximity of anchored bisazo chromophores and the capability of intermolecular forces between dyes producing hydrogen aggregates in solutions and thin films. (C) 2004 Wiley Periodicals, Inc.