Abstract
Two bichromophoric polyetherurethanes with a small number of pyrene rings on the quaternary ammonium groups and photoisomerizable azobenzene chromophore attached to the soft (AzPUC-Py1) or hard segment (AzPUC-Py2) of the polymeric backbone were synthesized and characterized. The effect of polymer structure on the trans–cis and cis–trans photo(thermo)isomerization of azobenzene in thin films induced by UV light (λ = 365 nm) was investigated using UV spectroscopy, and in every case the quality of sensitizer of the pyrene was not evidenced. Moreover, a better photochromic response in the film containing azobenzene in the polyether component compared to that induced of the same chromophore in the hard segment was registered. Properties in the solution and thin films were then examined in relation with the fluorescence of pyrene molecule excited at λ exc = 335 nm. Results of the fluorescence study accompanied of a fluorescence quenching through N,N-diethylaniline (DEA) sustain that these polymers could be used for the detection of amines up to a concentration of 1.57 × 10−3 mol/l (AzPUC-Py1) and 3.14 × 10−3 mol/l (AzPUC-Py2), respectively, in DMF solution. Compared to the polymer solution, in the polymer film exposed to DEA-saturated vapors about 30% monomer fluorescence quenching was found after 90 min.
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