Facile Fabrication of Absorption-Dominated Biodegradable Poly(lactic acid)/Polycaprolactone/Multi-Walled Carbon Nanotube Foams towards Electromagnetic Interference Shielding

Abstract

The use of electromagnetic interference shielding materials in the mitigation of electromagnetic pollution requires a broader perspective, encompassing not only the enhancement of the overall shielding efficiency (SET), but also the distinct emphasis on the contribution of the absorption shielding efficiency within the total shielding efficiency (SEA/SET). The development of lightweight, biodegradable electromagnetic interference shielding materials with dominant absorption mechanisms is of paramount importance in reducing electromagnetic pollution and the environmental impact. This study presents a successful fabrication strategy for a poly(lactic acid)/polycaprolactone/multi-walled carbon nanotube (PCL/PLA/MWCNT) composite foam, featuring a uniform porous structure. In this approach, melt mixing is combined with particle leaching techniques to create a co-continuous phase morphology when PCL and PLA are present in equal mass ratios. The MWCNT is selectively dispersed within the PCL matrix, which facilitates the formation of a robust conductive network within this morphology. In addition, the addition of the MWCNT content reduces the size of the phase domain in the PCL/PLA/MWCNT composite, showing an adept ability to construct a compact and stable conductive network. Based on its porous architecture and continuous conductive network, the composite foam with an 80% porosity and 7 wt% MWCNT content manifests an exceptional EMI shielding performance. The SET, specific SET, and SEA/SET values achieved are 22.88 dB, 88.68 dB·cm3/g, and 85.80%, respectively. Additionally, the resulting composite foams exhibit a certain resistance to compression-induced deformations. In summary, this study introduces a practical solution that facilitates the production of absorption-dominated, lightweight, and biodegradable EMI shielding materials at scale.