Supramolecular engineered ultrathin MXene towards fire safe polylactic acid composites

The combustion of polymeric materials will generate a mass of heat and release poisonous fumes, which not only hinders the personnel escape and causes casualties, but also causes the environmental contamination. Herein, a novel N–P–Co-containing supramolecular assembly network (MHCSN) flame retardant was synthesized by electrostatic interaction and supramolecular self-assembly technology. Then, MHCSN-Ti 3 C 2 T x (MHCSN-TC) hybrids were synthesized by hydrogen bonding induced assembly and compounded with silicone wrapped ammonium polyphosphate (SiAPP) to successfully fabricate polylactic acid (PLA)/MHCSN-TC/SiAPP composites. PLA/MHCSN-TC/SiAPP composites exhibited the improved flame retardancy. For example, the introduction of 1.0 wt.% MHCSN-TC and 14.0 wt.% SiAPP into PLA resulted in significant reduction in the total heat release (50.1%), peak of heat release rate (64.1%) and peak of smoke production rate (61.3%). The improvements in flame retardance and smoke suppression of the PLA composites were due to the catalytic carbonization and barrier effect of the modified Ti 3 C 2 T x nanoflakes. Meanwhile, the generated phosphorus-containing radicals generated by SiAPP captured the H• and HO• produced from the PLA material, and these phosphorus-containing species evolved into compact expanded char layers. This work offers a simple method to prepare highly effective flame retardants for PLA. • N–P–Co-containing supramolecular assembly network flame retardant was synthesized. • MHCSN was uniformly distributed in Ti 3 C 2 T x nanosheets for Ti 3 C 2 T x /MHCSN hybrid. • PLA/MHCSN-TC/SiAPP hybrid showed markedly reduced heat and smoke release. • Reduced fire hazards are attributed to multiple effects of flame retardants.