Multifunctional Bacterial Cellulose Nanofibers/Polypyrrole (PPy) Composite Films for Joule Heating and Electromagnetic Interference Shielding

Polypyrrole has attracted more and more attention due to its low density, high conductivity, and excellent electro/photothermal conversion ability. However, the poor mechanical properties of polypyrrole limit its further application. In this work, mechanically flexible bacterial cellulose nanofibers/polypyrrole (BC@PPy) composite films were fabricated by in situ polymerization and vacuum filtration. The addition of BC improved the mechanical properties of PPy and made it have good tensile and bending capacity. The conductivity of BC@PPy films could be tuned by the polymerization time of pyrrole. The BC@PPy-6 h film displayed excellent low-voltage-driven Joule heating (up to 95.4 °C at 5 V) and high-efficiency photothermal conversion (up to 52.4 °C under 100 mW/cm2) performance. Moreover, the resultant BC@PPy-6 h film also showed outstanding electromagnetic interference (EMI) shielding effectiveness of exceeding 28.5 dB in the whole X band. Therefore, the multifunctional BC@PPy films possess high application prospects in wearable electrical devices for Joule heating, photothermal conversion, and EMI shielding.