【Frontiers in HaiChuan Chemical Technology】CAS team develops high-performance photopolymerizable 3D printing elastomers

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Recently, a research team from the Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, took advantage of the processing capabilities of their independently developed line-scanning photopolymerization 3D printing (LSVP) system for high-viscosity photosensitive resins. Addressing the issue of poor tear resistance in traditional photopolymerized elastomers, which is caused by the conflict between cross-linking and entanglement, they developed photopolymerized 3D printed elastomers that possess excellent tear resistance, self-healing properties, and recyclability. This advancement helps to expand the application of photopolymerization 3D printing technology in areas such as flexible devices and smart materials. The team adopted a strategy of grafting urea-pyrimidone (UPy) groups onto methacrylate-2-(tert-butylamino)ethyl ester-terminated polyurethane acrylate prepolymers, and optimized the crosslinking network by regulating the hydrogen bond density to develop a monomer-free photopolymerizable resin system. This system combines photothermal dual-curing technology with multiple hydrogen bond interactions to form a topological network that features both high-density chain entanglement and dynamic physical cross-linking, thereby achieving a synergistic effect between chain entanglement and physical cross-linking. The team further utilized the LVSP technique to address the challenges associated with printing high-viscosity resins, thereby minimizing the negative impact of reactive diluents on the material properties, and produced 3D-printed elastomers with high entanglement and low cross-linking. Performance tests show that the UPyA-0.10 elastomer exhibits excellent overall mechanical properties: a tensile strength of over 40 MPa, an elongation at break of approximately 1000%, and a toughness of more than 144 MJ m-3. Its resilience, tear resistance, and ductility all reach levels comparable to those of thermoplastic parts. This material exhibits excellent resistance to notched tearing and notched fatigue, with a fracture energy of 189.42 kJ m-2. The printed structures can withstand a tensile load of nearly 9.8 kg without crack propagation, and they possess good self-healing capabilities; they maintain stable mechanical properties even after multiple cuts and reprocessing, demonstrating outstanding reprocessability. This work overcomes the limitations associated with the tear resistance of traditional photopolymerized elastomers, offering new approaches for the design and fabrication of high-performance photopolymerized 3D printed elastomers. It holds promise for applications in areas such as flexible devices, structural protection, and medical devices.