Multifunctional UV‐NIR Dual Light‐Responsive Soft Actuators from a Main‐Chain Azobenzene Semi‐Crystalline Poly(ester‐amide) Doped with Polydopamine Nanoparticles

Abstract

AbstractThe development of soft photoactuators with multifunctionality and improved performance is highly important for their broad applications. Herein, we report on a facile and efficient strategy for fabricating such photoactuators with UV‐NIR dual light‐responsivity, room‐temperature 3D shape reprogrammability and reprocessability, and photothermal healability by doping polydopamine (PDA) nanoparticles into a main‐chain azobenzene semi‐crystalline poly(ester‐amide) (PEA). The PEA/PDA nanoparticle composite was readily processed into free‐standing films with enhanced mechanical and photomechanical properties compared with the blank PEA films. Its physically crosslinked uniaxially oriented films showed rapid and highly reversible photochemically induced bending/unbending under the UV/visible light irradiation at room temperature in both the air atmosphere and water. When exposed to the NIR light, they (and their bilayer films formed with a polyimide film) exhibited photothermally induced bending even at a temperature much lower than their crystalline‐to‐isotropic phase transition temperature based on a unique mechanism (involving photothermally induced polymer chain relaxation due to the disruption of their hydrogen bonds). The room‐temperature 3D shape reprogrammability and reprocessability and photothermal healability of the composite polymer films were also demonstrated. Such multifunctional dual light‐responsive photoactuators with well‐balanced mechanical robustness, actuation stability, 3D shape reprogrammability/reprocessability and photothermal healability hold much promise in various photoactuating applications.