Sandwich composites of polyurethane reinforced with poly(3,4-ethylene dioxythiophene)-coated multiwalled carbon nanotubes with exceptional electromagnetic interference shielding properties

Poly(3,4-ethylene dioxythiophene) (PEDOT)-coated multiwalled carbon nanotube (MWCNT) composite (PCNT) was synthesized by in situ emulsion polymerization and was used as a filler for the fabrication of polyurethane (PU) sandwich composites (PUPCNT) by a solution casting technique. Transmission electron microscopy (TEM) images revealed a coating of PEDOT over the MWCNTs, and scanning electron microscopy (SEM) micrographs showed uniform dispersion of PCNT filler in the fractured surfaces of PUPCNT films, which was further confirmed by X-ray diffraction (XRD) analysis. The tensile strengths of all the PUPCNT composites indicated that tensile strengths do not degrade on adding 10% and 20% PCNT filler in the PU matrix. Electrostatic charge dissipation (ESD) measurements of PEDOT filled PU composites showed a static decay time of 0.2 s, which indicates that they can be utilized for antistatic applications. The PUPCNT composites showed excellent electromagnetic interference shielding effectiveness (EMI SE) which increased with increasing filler loading in the PU matrix. The maximum EMI SE obtained was 45 dB with 30 wt% loading of PCNT filler in the frequency range of 12.4-18 GHz (Ku-band).