Three-dimensional printing of highly conductive polymer nanocomposites for EMI shielding applications

Here we applied three-dimensional (3D) printing of conductive microstructures for the functional optimization of lightweight and semi-transparent electromagnetic interference (EMI) shields. Highly conductive 3D printable inks with electrical conductivities up to ∼5000 S m⁻¹ were fabricated from carbon nanotubes/polylactic acid (CNT/PLA) nanocomposites. Solvent-cast 3D printing enabled us to fabricate conductive scaffold microstructures and investigate the influence of various important structural parameters (i.e., inter-filament spacing, number of layers and printing patterns) on their transparency and EMI shielding effectiveness. The results revealed a significant improvement of the specific EMI shielding effectiveness of CNT/PLA nanocomposites printed as 3D scaffolds compared to CNT/PLA hot-pressed in solid forms (∼70 vs ∼37 dB g⁻¹ cm³). The transparency of the scaffolds could vary from ∼0% to ∼75% by modifying their printing patterns and inter-filament spacing. To the best of our knowledge the conductivity of the fabricated ink is the highest among the other reported 3D printable polymer composite inks and this is the first reported systematic study on EMI shielding using a 3D printing technique. These results are highly beneficial for the fabrication and structural optimization of EMI shields where light and/or transparent structures are advantageous, such as in aerospace systems, portable electronic devices or smart fabrics.