Synthesis and properties of new polyurethanes with triazene moieties in the main chain

A new diol with bistriazene groups, 1,1′[4,4′-diphenylether]-3,3′-di(β-hydroxyethyl methyl)-bistriazene (BTD), was synthesized and characterized. BTD, along with N-methyldiethanolamine as a chain extender, was used to prepare a segmented polyurethane based on poly(tetramethylene oxide) diol (weight-average molecular weight = 2000) and 2,4-tolylene diisocyanate (80:20 v/v 2,4-/2,6-isomer mixture). Subsequent quaternization of the amine with benzyl chloride formed the cationomer. The structure–property relationships, including the photochemical behavior of the triazene linkage in these polymers, were investigated with respect to another polyurethane prepared from 4,4′-diphenylmethane diisocyanate and a bistriazene compound. Photolysis experiments were carried out in polymer solutions and in the film state, and the reduction of the π–π* absorption band, characteristic of the triazene chromophore in ultraviolet spectra, was followed. A kinetic evaluation revealed a first-order photoprocess. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 385–391, 2005