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 FeCl 3 , 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 dBm 2 ) 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.