Additive manufacturing has gained significant attention for applications requiring functional materials. In this study, a functional carbon nanotube (CNT) composite in the form of buckypaper (BP) was fabricated and integrated into laminated object manufacturing (LOM). CNT BPs with varying CNT contents were produced using a hybrid tape casting–vacuum filtration method, with 70 wt% CNT BP enabling successful printing under the tested conditions. These BPs were 3D structured into 3-layer and 5-layer configurations using both 3D printing (3DP) and manual stacking (MS) techniques. A comparative analysis was conducted of the structural, morphological, mechanical, electrical, and electromagnetic interference shielding properties. The 3DP structures maintained a consistent CNT content of 56 wt% and exhibited improved structural uniformity due to controlled adhesive application and processing load. Despite slightly lower tensile strength (13.5 MPa and 15.4 MPa for 3DP 3-layer and 5-layer structures, respectively) compared to MS structures (20.8 MPa and 24.6 MPa), the 3DP samples exhibited higher Young's modulus (372 MPa and 388 MPa) than the corresponding MS structures (295 MPa and 233 MPa). The CNT BP exhibited an in-plane electrical conductivity of approximately 45 S/cm, while the sheet resistance of the 3DP structures was approximately 1.06 to 1.10 Ω/sq., compared to 1.92 to 2.34 Ω/sq for the MS structures. Furthermore, the electromagnetic interference (EMI) shielding effectiveness increased from approximately 42 dB for single-layer CNT BP to 65 dB and 95 dB for 3-layer and 5-layer 3DP structures, respectively. This study introduces a new LOM-based approach for fabricating high–filler-content functional composites for EMI shielding and future advanced applications.
The remarkable properties of carbon nanotubes (CNTs) make them highly valuable materials across a wide range of application fields. For this reason, there is considerable interest in developing innovative and sustainable functionalization strategies that can improve CNTs dispersion by introducing chemical functionalities, which can impart them specific features. Herein, we report a sustainable and efficient approach for the covalent modification of single- (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) using disulfide derivatives as components of newly developed eutectic mixtures (EMs). Differential scanning calorimetry (DSC) confirmed the formation of EMs through a marked melting point depression relative to the pure components. By combining selected disulfides with appropriate hydrogen bond donor (HBD) and acceptor (HBA) species, six EMs were prepared and employed as reactive dispersion media of CNTs enabling the in situ generation of thiyl radicals. This methodology drastically reduces reaction volumes, shortens processing times, and limits the use of volatile organic solvents. The resulting hybrid materials, bearing hydroxyl, carboxyl, or amine groups, were characterized by thermogravimetric analysis (TGA), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). This EM-assisted strategy provides a greener and more convenient route for CNTs functionalization and offers a versatile alternative for producing advanced carbon-based materials with potential applications.
