Tough Body Temperature-Triggered Shape Memory Silicone-Based Elastomers via Segment Sequence Regulation Strategy.

Developing high-strength, tough, shape-memory, and self-healing PDMS elastomers is crucial for flexible electronics and biosensing. Nevertheless, synergistically improving all these properties is challenging due to their intrinsically low glass transition temperature, amorphous nature, and weak intermolecular interactions. Herein, a molecular strategy by regulating the segment sequences is proposed to create multifunctional PDMS elastomers with tunable mechanical properties. Specifically, well-designed chain segment sequences can optimize the microphase separation structure. This strategy endows the elastomer with tunable mechanical properties, including high strength (18.9 MPa), high elongation (770%), and high toughness (50.7 MJ m- 3). Surprisingly, the optimal elastomer exhibits a widely tunable shape memory effect, governed by the dissociation degree of its reversible hydrogen bonds, which remains effective even at temperatures approaching human skin (36.5°C). Multiple dynamic hydrogen bonds give elastomers excellent self-healing and weldability. As proof, a self-locking biosignal detection device is successfully constructed by welding this versatile elastomer to encapsulate a commercial pulse sensor. The self-locking of the wristband, triggered by shape memory, improves the signal monitoring stability. This work provides a molecular perspective for designing high-performance elastomers and expands the application of smart elastomers in advanced soft devices.