Joule-heat derived amorphous/graphitic polymer nanotubes with enhanced electromagnetic wave absorption and high thermal conductivity

The rapid advancement of artificial intelligence demands multifunctional materials integrating electromagnetic wave absorption (EWA) and thermal management capabilities for next-generation electronics. Herein, a facile and scalable Joule-heating carbonization strategy is proposed to regulate the amorphous-to-graphitic phase ratio in polymer nanotubes, achieving a precise modulation of EWA performance. The nitrogen species transformation during carbonization induced enhanced polarization relaxation, defect generation, and dipole polarization, synergistically facilitating charge transfer. Polypyrrole-based polymer nanotubes treated at 1000 o C (PNT-1000) exhibited a maximum effective absorption bandwidth of 3.46 GHz and a minimum reflection loss of −45.1 dB. Moreover, PNT-1000@polydimethylsiloxane (PDMS) demonstrated a thermal conductivity of 2.26 W/(mK), while PNT-2000@PDMS achieved a significantly higher thermal conductivity of 4.20 W/(mK). This work systematically elucidated the interaction between amorphous and graphitic phases in controlling both EWA and thermal conductivity, which is helpful for applying carbon-based materials in these advanced fields.