Multifunctional modifier coupled with premixing for PLA/CNT composites with ultra‑high toughness and superior functionality

Polymer/carbon nanotube (CNT) nanocomposites are promising structural-functional integrated materials, but achieving ultra-high toughness and excellent functionality for rigid polymer/CNT composites remains challenging. Herein, a strategy combining a multifunctional modifier and premixing technique was developed to synchronously achieve the ultra‑high toughness and enhanced functionality of poly(lactic acid) (PLA)/CNT composites, a representative of rigid polymer/CNT nanocomposites. The modified tannic acid (mTA), featuring low T g , abundant benzene rings and grafted isopropanol oligomers, serves as a multifunctional modifier to toughen PLA/CNT composites, establish π-π interactions with CNTs and form hydrogen bonding with PLA. Premixing CNTs with sufficient mTA favors the coating of CNTs by mTA, enabling mTA to effectively inhibit CNT re-agglomeration. Consequently, this strategy synchronously optimizes CNT dispersion, enhances interfacial adhesion, and toughens PLA/CNT composites. The optimal PLA/mTA15/CNT2 achieves an unprecedented integration of ultra-high toughness (165.1 ± 9.3 MJ/m 3 ) and obviously improved functionality (electrical conductivity and EMI shielding effectiveness). The composite also exhibits superior melt processability and 3D printability, enabling the fabrication of complex components. This work offers a promising route for developing high-performance structural–functional integrated materials, and will promote the practical applications of PLA/CNT composites in antistatic packaging, flexible electronics, and electromagnetic interference shielding materials.