Multifunctional PLA/E-GMA/CB conductive polymer composites exhibiting enhanced toughness, electrically triggered shape memory, and EMI shielding

Conductive polymer composites (CPCs) capable of combining electrical functionality with high impact resistance remain relatively unexplored, since the incorporation of conductive fillers typically reduces the toughness of polymeric matrices. Here, we report multifunctional polylactic acid/ethylene-glycidyl methacrylate/carbon black (PLA/E-GMA/CB) composites in which a selectively localized CB network within the E-GMA phase simultaneously enhances toughness, imparts tunable electrical conductivity, and enables electrically triggered shape memory response. The co-continuous PLA/E-GMA morphology was preserved across all CB loadings, while filler confinement in the elastomer-rich domains promoted efficient stress dissipation and reduced the percolation threshold. Impact strength increased from 150 J/m (blend) to 450 J/m at 12 phr CB, without compromising modulus. Electrical conductivity rose by seven orders of magnitude, reaching ∼10 −5 S/cm, sufficient for Joule-heating-induced actuation and powering LEDs. All formulations exhibited nearly complete shape fixity (∼100%) and recovery ratios above 78% under thermal activation, while electrically triggered specimens achieved recovery levels of approximately 90%. Moreover, the composites delivered electromagnetic interference (EMI) shielding effectiveness (SE) up to 25 dB in the 3.25–6 GHz band. These results demonstrate a synergistic design strategy for developing composites that integrate toughness, electrical functionality, shape memory activation, and EMI protection, enabling emerging applications in smart devices.