(560a) Light-Induced Mechanical Response in Poly(alkylurea urethane) Networks Containing Azobenzene Compounds

Structural polymeric materials, such as thermosets, are typically designed to operate in the glassy state. The ability to switch mechanical properties or turn on adhesion would simplify fabrication of thermoset laminates and promote reusability. One challenge of accessing the benefits of dynamic bonds in polymeric systems is their often limited ability to rearrange when the polymer is in the glassy state. We demonstrate the ability to induce a mechanical response in poly(alkylurea urethane) networks under dynamic loading with the exposure of UV light and the inclusion of azobenzene derivatives. The location of the azobenzene derivatives (in the backbone, as a pendant group, or in the network volume), the bond activation energy of the hindered amine, and proximity of the azobenzene derivative to the hindered urea dictate the degree of the mechanical response.