Azo-Bridged Dextran:A Photoresponsive SustainableMaterial with Photo-Tunable Mechanical Properties

We report on the synthesis, characterization, and properties of dextran polymers, which are covalently bridged/cross-linked by azobenzene moieties. The reversible photoactivity of the azo moiety is retained in the polymers, and the kinetics of the <i>E</i>/<i>Z</i> isomerization depend on the dextran/azobenzene ratio. Together with the simple preparation, our approach provides convenient access to photoresponsive sustainable materials. Moreover, based on the water-soluble polymers, we have prepared photoresponsive hydrogels, which soften upon UV irradiation. Our findings are based on spectroscopy (UV/vis, IR, and NMR/DOSY), size exclusion chromatography, and rheology.