Two‐Photon Polymerized Poly(ε‐caprolactone) Microstructures with Shape‐Memory Behavior Under Compressive Loading

ABSTRACT Shape memory polymers capable of recovering their original form after deformation are highly desirable for applications in soft robotics, biomedical engineering, and microfabrication. However, integrating shape memory properties into 3D‐printed microstructures with ultra‐low mass remains a challenge, as most existing systems lack sufficient resolution or mechanical robustness at the microscale. In this study, a poly(ε‐caprolactone)‐based material, crosslinked via thiol–ene chemistry, is developed to fabricate mechanically stable 3D‐microstructures using two‐photon polymerization. This process enables sub‐micron features down to approximately 550 nm. Printing parameters, including laser power, scan speed, hatch distance, and layer height, are optimized to produce complex micro‐architectures with high CAD‐CAM fidelity. Micrometer‐scale geometries are successfully printed, including hollow scaffolds weighing 0.89 µg. These scaffolds exhibit excellent shape memory behavior, fully recovering their original shape upon heating even after compressive loads exceeding five million times their own weight. This microscale demonstration confirms that shape memory functionality translates reliably from macro‐ to microscale without compromising structural integrity. Macroscale dynamic mechanical analysis shows excellent shape fixity (R f >99.45%) and shape recovery ratios (R r >99.07%) across multiple thermal cycles, while nanoindentation validates microscale stiffness and structural integrity.