Polydopamine-functionalized MXene nanoplatelets for enhanced impact resistance and dynamic mechanical performance of injection-molded PLA composites

The development of robust and environmentally sustainable polymer composites remains a key objective across advanced manufacturing sectors. In this study, poly (lactic acid) (PLA) composites were prepared via a facile melt-blending approach incorporating surface-modified MXene (Ti3C2Tₓ) nanoplatelets. The MXene was functionalized with polydopamine (PDA), introducing abundant active groups that enhanced interfacial interactions with the PLA matrix through hydrogen bonding. Composites were prepared with varying loadings of pristine and PDA-treated MXene (0.5, 1.0, and 1.25 wt.%). Surface modification was verified using FTIR, XPS, SEM and XRD analyses. The resulting PDA@Ti3C2Tₓ/PLA composites exhibited improved dispersion and significantly enhanced impact strength, dynamic mechanical performance, and crystallization behavior. Notably, the PM1 sample (1 wt.% PDA@MXene) achieved a 37.77% increase in impact resistance (3.10 kJ/m2) compared to neat PLA. Cold crystallization temperature (Tcc) decreased from 125.66°C to 114.83°C, while enthalpy of cold crystallization (ΔHcc) increased from 10.44 J/g to 23.15 J/g, indicating effective nucleation. These outcomes highlight the promise of PDA-functionalized MXene as a multifunctional reinforcement for high-performance, sustainable PLA-based composites.