Killing three birds with one stone: A novel regulate strategy for improving the fire safety of thermoplastic polyurethane

Flammable and highly toxic smokes are roadblocks for thermoplastic polyurethanes (TPU) in high-tech applications. Herein, we reported polydopamine (PDA) as a functional adjuvant for the synthesis of ZIF-8@PDA@Cu nanohybrids with a “Killing three birds with one stone” strategy, modulating the morphology and dispersion of ZIF-8, providing excellent adhesion capability to enhance the complexation of copper (Cu) particles, and playing a flame retardant function. The ZIF-8@PDA@Cu nanohybrids presented a homogeneous dispersion and built up robust interfacial interactions with TPU substrate. Further, TPU/ZIF-8@PDA@Cu composites exhibited excellent thermal stability, flame resistance and toxic smoke inhibition performance, as evidenced by high char residuals, low peak heat release rate (59.2% reduction), low peak smoke production rate (54.3% reduction) and low peak CO production (40.7% reduction). Because of the physical barrier effect of stable char layer, dilution effect of non-combustible gas and free radical scavenging effect of catechol groups, TPU composites were endowed with an excellent fire safety. Notably, metal compounds formed by thermal degradation of ZIF-8@PDA@Cu nanohybrids were able to undergo cyclic redox reaction with carbon monoxide, significantly decreased the release of toxic gas.