Physiologically Triggered Shape Memory Elastomers Based on Hierarchical Block Copolymer

Traditional actuation mechanisms for biomedical shape memory polymers exhibit prohibitive limitations, including the severe risk of localized thermal tissue necrosis, a reliance on cumbersome external triggering equipment, and the potential long-term toxicity introduced by nonbiodegradable conductive fillers. Herein, this study designed an amphiphilic block copolymer (PBSEG-b-PEG-U) by randomly copolymerizing hydrophilic polyethylene glycol (PEG) microdomains into a hydrophobic polybutylene succinate (PBS) backbone. This specific macromolecular architecture effectively pairs the rigid PBS stationary phase with the highly responsive PEG recovery phase, creating a synergistic water-driven dynamic response. Experimental findings reveal that through simple adjustment of the feed ratio, the phase transition temperature of the copolymer urethane can be controlled near human body temperature (36.4 °C). Meanwhile, PBSEG-b-PEG-U exhibits a favorable recovery rate approaching 100% in water at 37 °C, enabling noninvasive autonomous actuation in vivo applications. In addition, the polyurethane also exhibits excellent mechanical properties (with an elongation at break of 1523%) and good water absorption (55.6%).