Physiologically Triggered Shape Memory Elastomers Based on Hierarchical Block Copolymer

Abstract

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%).