Ultralow-Threshold and Lightweight Biodegradable Porous PLA/MWCNT with Segregated Conductive Networks for High-Performance Thermal Insulation and Electromagnetic Interference Shielding Applications

TLDR

Lightweight, biodegradable, thermally insulating, and electrically conductive materials are essential for sustainable development, yet creating such multifunctional materials remains challenging. The study aims to develop a general, facile, eco‑friendly method for large‑scale fabrication of ultralow‑threshold biodegradable porous PLA/MWCNT for high‑performance thermal insulation and EMI shielding. The method embeds conductive 3‑D MWCNT networks into a microporous PLA matrix, yielding a lightweight composite with an ultralow percolation threshold. The resulting porous PLA/MWCNT (density 0.045 g cm⁻³) achieves a percolation threshold of 0.00094 vol %, a thermal conductivity of 27.5 mW m⁻¹ K⁻¹, and an absorption‑dominated EMI shielding effectiveness of 1010 dB cm³ g⁻¹, surpassing existing materials.

Abstract

Lightweight, biodegradable, thermally insulating, and electrically conductive materials play a vital role in achieving the sustainable development of our society. The fabrication of such multifunctional materials is currently very challenging. Here, we report a general, facile, and eco-friendly way for the large-scale fabrication of ultralow-threshold and biodegradable porous polylactic acid (PLA)/multiwalled carbon nanotube (MWCNT) for high-performance thermal insulation and electromagnetic interference (EMI) shielding applications. Thanks to the unique structure of the microporous PLA matrix embedded by conductive 3D MWCNT networks, the lightweight porous PLA/MWCNT with a density of 0.045 g/cm3 possesses a percolation threshold of 0.00094 vol %, which, to our knowledge, is the minimum value reported so far. Furthermore, the material exhibits excellent thermal insulation performance with a thermal conductivity of 27.5 mW·m-1·K-1, which is much lower than the best value of common thermal insulation materials. Moreover, it also shows outstanding EMI shielding performance characterized by its high shielding effectiveness (SE) values and absorption-dominated shielding feature. More importantly, its specific EMI SE is as high as 1010 dB·cm3·g-1, which is superior to those of other shielding materials reported so far. Thus, this novel multifunctional material and its general fabrication methodology provide a promising way to meet the growing demand for high-performance multifunctional materials in sustainable development.