4D‐Printable Bio‐Based Thermoplastic Polyurethane With Body‐Heat‐Induced Shape Memory Behavior

Shape memory polymers (SMPs) and their composite counterparts (SMPCs) comprise a class of intelligent materials capable of reverting to their original shapes when stimulated by specific external cues. Among their notable functionalities, the shape memory effect (SME) has garnered increasing attention due to its unique thermal and electrical actuation capabilities. These materials exhibit reversible deformation behavior upon exposure to specific triggers such as heat or electrical signals, which enable a variety of structural transformations. This study focuses on recent developments in the fabrication of temperature‐responsive SMPs, particularly in the context of 4D printing technologies, which aim to enhance both mechanical performance and SME characteristics. A novel class of bio‐based thermoplastic polyurethanes (TPUs) was synthesized with 100% renewable sources. The soft segment consisted of poly(propylene succinate) (PPS) derived from corn glucose, while 1,3‐propanediol was utilized as a bio‐based chain extender. The prepolymer was formed using dicyclohexylmethane diisocyanate (H 12 MDI), yielding materials with reliable shape recovery near human body temperature (36.5°C). Additionally, this study demonstrates the fabrication of thermally responsive 4D‐printed metamaterials and discusses recent approaches for controlling soft actuators, providing direction for future developments in programmable polymer systems.