Cl−‐Doped Polypyrrole Nanotubes Toward Robust Thermal Dissipation and Tunable Microwave Absorbing/Shielding Properties

Abstract

Developing multifunctional electromagnetic (EM) protection materials with high thermal conductivity is of great significance for next‐generation wearable electronics. However, balancing the different functionalities is a challenging task due to performance incompatibility. Therefore, this study aims to develop Cl−‐doped PPy nanotubes as a new multifunctional EM protection material via a simple soft template‐assisted oxidation polymerization process. The Cl− doping level and nanotube structure are precisely tuned by controlling the concentrations of MO and FeCl3, benefiting not simply conductivity but multiple polarizations and thermal transfer rates. Theoretical analyses confirm that controlling the Cl− doping level can adjust the PPy energy band structure and enable its conversion from semiconductor to conductor. The Cl−‐doped PPy nanotubes (PPy‐M‐4) exhibit efficient wide‐band microwave absorption (3.32 GHz mm−1) and RCS reduction (33.45 dBm2) at a 4 wt.% load, and attain a high EMI SE value of 66.36 dB with 99.9% shielding over 2–18 GHz at a 20 wt.% load. Furthermore, the Cl−‐doped PPy nanotubes/silicone membranes possess high tensile strength, exceptional flexibility, and high thermal conductivity (3.597 W m−1 K−1), resulting from their 3D‐interconnected network, electrons, multifrequency active phonons, and coupling. These properties outperform those of most other materials.