Assembly of a micro-carbonized lignin-cellulose mixture and carbon nanotubes via interfacial interactions to prepare a composite film with superior electromagnetic interference shielding and mechanical performance

Abstract

The conductive polymer composite (CPC) is a superior material because of its flexibility and lightweight properties, revealing high application potential in the electromagnetic interference (EMI) shielding field. However, the poor mechanical properties, conductivity, and EMI shielding efficiency hinder its development. Research studies show that engineering interfacial interactions (electrostatic interaction, van der Waals interaction, π–π bridging, etc.) between carbon nanotubes (CNTs) and the polysaccharide matrix can regulate the microtopography of the composite, which is the key to solving the above dilemma. Herein, sodium lignosulfonate (L) and a carboxymethyl cellulose (CMC) mixture were microcarbonized into novel carbon dots (CDs), named LCCD, where the CDs were grafted on CMC chains. The as-prepared LCCD chains were added into a CMC and CNT suspension to fabricate a CMC-LCCD-CNT film. The CMC-LCCD-CNT film showed high EMI shielding (82.6 dB), conductivity (1386.57 S cm⁻¹), and mechanical performance (a tensile strength of ∼748.6 MPa, Young's modulus of ∼28.6 GPa and toughness of 24.1 MJ m⁻³) on account of its strong interfacial interactions between the LCCD chains and CNT. Notably, the addition of CMC in the LCCD preparation could increase entanglement and plastic deformation between the components in the CMC-LCCD-CNT film, which was conducive to engineering the interfacial interactions of the composite and further improved its corrosion resistance, EMI shielding and mechanical properties, exhibiting great potential for working in severe environments.