Polymers capable of controlled degradation are especially attractive from a sustainability perspective and enable stimuli-responsive alteration of mechanical properties at will. Herein, we present the synthesis of new aliphatic azo-containing polyurethanes and their degradation in response to heat and light, both in the solid and solution states. The relatively stable radical forming azo monomer present in the polyurethane readily undergoes thermal degradation leading to a decrease in molecular weight in the polymer and a shift in mechanical properties. In contrast, the azo-group was comparatively less susceptible to UV treatment. We contrasted the stimuli-responsiveness of these materials with previous azo-containing polymers and demonstrated clear correlations between the controlled degradation process and both the azo stability and the nature of the host polymer. Our results highlight the importance of radical activity in azo-containing polymers and opens up new pathways for multi-responsive systems.

Leveraging azo stability for stimuli responsive mechanomorphing in polyurethanes

ACS Fall 2021

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