Dielectric and EMI shielding properties of Mn₃O₄ nanoparticle-decorated MWCNTs embedded bio-benzoxazine cross-linked poly(o-phenylenediamine) composites

We introduce a novel polymer nanocomposites (EGBZO/POPDA/Mn₃O₄–MWCNT), having remarkable electromagnetic interference shielding efficiency, incorporating Mn₃O₄ nanoparticle-decorated MWCNTs, bio-benzoxazine (EGBZO), and poly(o-phenylenediamine) (POPDA) in cross-linked membranes. The dispersion of Mn₃O₄ nanoparticle-decorated MWCNTs in the polymer matrix has been confirmed by the PXRD and FE-SEM image analysis. Overall, 30.2% of the residue remains undecomposed in the EGBZO/POPDA/Mn₃O₄–MWCNT after 800°C and demonstrates the thermal stability of the prepared composites. EGBZO/POPDA has a dielectric loss of 4.5 × 10⁵ at 1 MHz. The dielectric loss values of QBZO/PANI increase proportionately with the addition of Mn₃O₄–MWCNTs at concentrations of 1%, 3%, and 5%, reaching 1.1 × 10⁶, 1.5 × 10⁶, and 2.8 × 10⁶ at 1 MHz, respectively. With increasing frequency at 9.5 GHz, the EGBZO/POPDA/Mn₃O₄–MWCNTs (5 wt%) polymer nanocomposite achieves an EMI shielding performance of 61.2 dB at a thickness of 2 mm. The improved EMI SE of this composite highlights its performance and potential for advanced shielding applications.