From Smart Denpols to Remote-Controllable Actuators: Hierarchical Superstructures of Azobenzene-Based Polynorbornenes

For the demonstration of remote-controllable actuators, a dendronized polymer (denpol) is newly designed and successfully synthesized by ring-opening metathesis polymerization of azobenzene-based macromonomers. The incorporation of azobenzene mesogens into the denpols helps to construct finely tuned hierarchical superstructures with anisotropic physical properties and reversible photoisomerization. The polynorbornene backbones and azobenzene side chains in the uniaxially oriented films are aligned perpendicularly and parallel to the layer normal, respectively. Based on photoreversible actuation experiments combined with diffraction results, direct relationships between the chemical structures, hierarchical superstructures, and their corresponding photomechanical behaviors are proposed. Smart denpols possess great potential for practical applications in photoresponsive switches.