Vat photopolymerization printing of strong tear‐resistance and stretchable polyurethane elastomer for highly sensitive strain sensors

Herein, a polyurethane elastomer reinforced with SiO2 nanoparticles modified with 3‐(trimethoxysilyl) methacrylate was proposed, enabling outstanding tensile, tear resistance and suitability for a variety of complex applications. The introduction of modified SiO2 nanoparticles has augmented the crosslink density among the molecular chains. The prioritized fracture of sacrificial bonds and chain entanglement can extend the local damage at the crack tip to the whole elastomer network. This effect might significantly improve the efficiency of energy dissipation, as well as prevent the crack propagation. The polyurethane elastomer, which consists of 0.5% modified nano‐SiO2, demonstrated a tear strength of 23.4 N/mm and superior mechanical stability, surpassing most commercial photocurable 3D printed polyurethane elastomers available commercially. Subsequently, polyurethane composite nano‐SiO2/LiTFSI (PSL) strain sensors with various flexible architectures were fabricated using DLP 3D printing technology by incorporating LiTFSI ionic liquid. The PSL strain sensor exhibited long‐term operational stability and high sensitivity, showing a considerable potential in the field of electronics. Overall, this study has opened up new opportunities for 3D printing of smart structured wearable devices with high performance. Highlights We constructed a SiO2 nanoparticle which can be used as a crosslinking agent of polyurethane molecular chain. The polyurethane elastomer doped with SiO2 nanoparticles is endowed with an excellent tear resistance. The LiTFSI composite PPU strain sensor constructed by DLP exhibited long‐term operational stability and high sensitivity. Conductive photosensitive polyurethane composite and PSL strain sensor.