DOPO-Decorated\nTwo-Dimensional MXene Nanosheets for\nFlame-Retardant, Ultraviolet-Protective, and Reinforced Polylactide\nComposites

Abstract

This\nstudy presents a novel and facile strategy for fabricating\nfire-resistant, ultraviolet (UV)-shielding, and tensile-enhanced polylactide\n(PLA) composites using two-dimensional (2D) MXene (Ti₃C₂) flakes chemically modified with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide\n(DOPO). The thermal and burning performances of PLA composites were\ndemonstrated by the limiting oxygen index, UL-94 test, and cone calorimetry.\nThe UV-shielding and tensile performances were also examined. The\nresults revealed that PLA/Ti₃C₂–DOPO\n(3 wt %) displayed a V-0 rating in the UL-94 test. The enhancement\nagainst fire hazard was reflected by the significant reduction in\nthe peak heat release rate (33.7%), total heat release (47%), peak\nCO production (58.8%), and total smoke production (41.7%). The improved\nfire-safety performance of the composites is attributed to the interplay\nof catalytic, barrier, and condensed effects of the Ti₃C₂–DOPO nanosheets in the PLA matrix. PLA/Ti₃C₂–DOPO also showed an increase (∼9%)\nin tensile strength and an “Excellent” level (UPF 50+)\nin the UV-protection assessment. In all, this study introduces a novel\nchemical modification strategy for 2D MXene flakes to fabricate multifunctional\nPLA composites, which are promising candidates for next-generation\nsustainable and protective plastic products.