Three-dimensional-printable polylactic acid/Eucommia ulmoides gum composites with silver nanoparticle-coated carbon fiber fillers and gradient triply periodic minimal surface structures for electromagnetic shielding and thermal management

Conventional electromagnetic interference (EMI) shielding materials remain heavily mold-dependent. This constrains design freedom, limiting structural customizability and manufacturing flexibility for modern electronics. This study successfully fabricated multifunctional polylactic acid/ Eucommia ulmoides gum/silver-coated carbon fiber (PLA/EUG/CF@Ag) composites via fused deposition modeling (FDM) three-dimensional (3D) printing. Uniform dispersion and aligned orientation of CF@Ag within the polymer matrix were achieved through ball milling and twin-screw extrusion, constructing efficient conductive and thermal networks. A gradient porous structure based on triply periodic minimal surfaces (TPMS) was designed and printed, which significantly enhanced electromagnetic wave absorption and heat dissipation. With a CF@Ag loading of 25 wt%, the composite exhibited a total electromagnetic interference shielding effectiveness (EMI SE) of 36 dB in the X-band (8.2–12.4 GHz). Compared to solid board structures, the gradient structure improved heat dissipation efficiency by 230% while simultaneously reducing the electromagnetic wave reflection coefficient from 0.90 to 0.68, demonstrating superior reflection-reduced shielding. This work provides a novel strategy for developing lightweight, customizable, and multifunctional electromagnetic interference shielding materials with promising applications in electronic packaging and aerospace.