Mechanically Robust, Reprocessable Shape Memory Fluorosilicon Materials Using β-H Elimination Reaction and in Situ Interfacial Compatibilization

Azo-Functionalized Thermoplastic Polyurethane for Light-Driven Shape Memory Materials

Shape memory polymers have great potential in the fields of soft robotics, injectable medical devices, and as essential materials for advanced electronic devices. Herein, light-triggered shape-memory thermoplastic polyurethane (TPU) is reported using azido TPU grafted by the photoswitchable azo compound. The trans-cis transitions of the azobenzene on the side chain of the TPU induce the recoiling of the main chain, leading to shaping memory behavior. Under UV irradiation, cis-azo allows the oriented main chain to recoil to release residual stress and realize light-triggered shape memory behavior. The facile method proposed here for the preparation of azo-functionalized TPU can provide viable opportunities for soft robotics and smart TPU applications.

Toward Robust, Tough, Self-Healable Supramolecular Elastomers for Potential Application in Flexible Substrates

A robust, tough, and self-healable elastomer is a promising candidate for substrate in flexible electronic devices, but there is often a trade-off between mechanical properties (robustness and toughness) and self-healing. Here, a poly(dimethylsiloxane) (PDMS) supramolecular elastomer is developed based on metal-coordinated bonds with relatively high activation energy. The strong metal-coordination complexes and their corresponding ionic clusters acting as the cross-linking points strengthen the resultant supramolecular networks, which achieves superior mechanical robustness (2.81 MPa), and their consecutive dynamic rupture and reconstruction efficiently dissipate strain energy during the stretching process, which leads to an impressive fracture toughness (32 MJ/m³). Additionally, the reversible intermolecular interactions (weak hydrogen bonds and strong sacrificial coordination complexes/clusters) can break and re-form upon heating; thus, the elastomer self-heals at a moderate temperature with the highest healing efficiency of 95%. As such, the potential of the as-prepared supramolecular elastomer for a substrate material of flexible electronic devices is discovered.

Strengthened, Antibacterial, and Conductive Flexible Film for Humidity and Strain Sensors

With the development of artificial intelligence, people are not satisfied with the traditional conductive materials and tend to focus on stretchable and flexible electronic systems. Flexible conductive rubbers have great potential applications in wearable strain sensors. However, the rapid propagation of bacteria during the use of wearable sensors may be an ineluctable threat to humans' health. Herein, a conductive rubber film is fabricated based on carboxylic styrene-butadiene rubber (XSBR), citric acid (CA), and silver nitrate (AgNO₃) via a convenient approach, where Ag nanoparticles (Ag NPs) are in situ reduced without sintering at elevated temperatures. The resultant films exhibit many desirable and impressive features, such as strengthened mechanical properties, flexibility, and conductivity. More importantly, the Ag NP flexible conductive films exhibit excellent antibacterial activity against Escherichia coli (Gram-negative bacteria) and Staphylococcus aureus (Gram-positive bacteria), which have potential applications as flexible antibacterial materials to monitor movements of the human body in real time. Also, because of the hygroscopicity of CA, the resistance of our conductive film is sensitive to various humidities, which can be applied in the humidity sensor.