UV cross-linkable hybrid resins for additive manufacturing to achieve high performance and body-temperature programmable shape memory effect¹

Since the introduction of 4D printing in 2012, shape memory hybrids (SMHs) have emerged as a versatile solution for tailoring thermomechanical properties. This study developed UV cross-linkable hybrid resins for additive manufacturing (AM) with high performance and body-temperature programmable shape memory effect (SME). These resins combine polycaprolactone (PCL) as the transition component with a commercial elastic UV cross-linkable resin. The thermomechanical properties and shape memory performance were evaluated using differential scanning calorimeter, Shore hardness, and tensile tests. The SMHs exhibited tuneable properties and excellent SMEs, with shape fixing and recovery ratios exceeding 97.5% for 40% PCL (PCL-40). Increased PCL content improved Shore hardness at room temperature while enabling softness near body temperature for easy programming. Feasibility for AM was demonstrated using extrusion-based and volumetric additive manufacturing techniques. Proof-of-concept experiments showed successful 2D-to-3D shape transitions programmed at body temperature with full recovery upon reheating. These findings highlight the potential of UV cross-linkable SMHs for applications in wearable devices, medical tools, and other technologies requiring body-temperature shape adaptation.