Constructing a multifunctional reactive MXene-based additive for micro-crosslinking polyurea elastomer to achieve superior mechanical properties and enhanced fire safety.

[Display omitted] • Synthesized a multifunctional reactive additive MX-SP-NH 2 and used it to prepare micro-crosslinked polyurea (PUA) elastomers. • It exhibited superior mechanical properties, compared with reported work. • The fire safety of the PUA was improved, showing significantly reduced heat release, smoke production, and CO production. • We prepared flexible strain sensors based on micro-crosslinked PUA, showing stable electrical signal responsiveness. The widespread application of polyurea (PUA) in protective coatings typically requires excellent flame retardancy due to real-world usage scenarios. However, the addition of flame retardant additives often compromises the material's mechanical properties. In this study, a multifunctional reactive additive, MX-SP-NH 2 , was creatively prepared by covalently grafting spirocyclic pentaerythritol bisphosphorate disphosphoryl chloride (SPDPC) onto MXene (Ti 3 C 2 T x) surfaces, followed by the introduction of 1,3-propanediamine (PDA) by the reaction with SPDPC. MX-SP-NH 2 was then incorporated into PUA, participating in its crosslinking process and significantly enhancing both its mechanical strength and flame retardancy. Compared to the control PUA sample, the micro-crosslinked PUA sample with just 1.0 wt% MX-SP-NH 2 demonstrated a 184.3% increase in tensile strength, a 126.1% increase in elongation at break, and a 436.3% increase in toughness. The flammability characterization revealed that the peak heat release rate, peak smoke production rate, and peak CO production rate were reduced by 31.7%, 28.9%, and 61.5%, respectively, indicating a substantial improvement in fire safety. Additionally, the flame retardant PUA-based flexible strain sensors demonstrated stable electrical signal responsiveness. This work has opened up new potential applications of PUA in flexible electronics. [ABSTRACT FROM AUTHOR]