Ultrarobust, Self-Healing\nPoly(urethane-urea) Elastomer\nwith Superior Tensile Strength and Intrinsic Flame Retardancy Enabled\nby Coordination Cross-Linking

Poly(urethane-urea) elastomers (PUUEs) have gained significant\nattention recently due to their growing demand in electronic skin,\nwearable electronic devices, and aerospace applications. The practical\nimplementation of these elastomers necessitates many exceptional properties\nto ensure robust and safe utilization. However, achieving an optimal\nbalance between high mechanical strength, good self-healing at moderate\ntemperatures, and efficient flame retardancy for poly(urethane-urea)\nelastomers remains a formidable challenge. In this study, we incorporated\nmetal coordination bonds and flame-retarding phosphinate groups into\nthe design of poly(urethane-urea) simultaneously, resulting in a high-strength,\nself-healing, and flame-retardant elastomer, termed PNPU-2%Zn. Additional\nsupramolecular cross-links and plasticizing effects of phosphinate-endowed\nPUUEs with relatively remarkable tensile strength (20.9 MPa), high\nelastic modulus (10.8 MPa), and exceptional self-healing efficiency\n(above 97%). Besides, PNPU-2%Zn possessed self-extinguishing characteristics\nwith a limiting oxygen index (LOI) of 26.5%. Such an elastomer with\nsuperior properties can resist both mechanical fracture and fire hazards,\nproviding insights into the development of robust and high-performance\ncomponents for applications in wearable electronic devices.