Flexible, ultrathin and light films from one-dimensional nanostructures of polypyrrole and cellulose nanofibers for high performance electromagnetic interference shielding

Combining highly conducting one-dimensional nanostructures of polypyrrole with cellulose nanofibers (CNF) into flexible films with tailored electrical conductivity and mechanical properties presents a promising route towards the development of eco-friendly electromagnetic interference shielding devices. Herein, conducting films with a thickness of 140 μm were synthesized from polypyrrole nanotubes (PPy-NT) and CNF using two approaches, i.e., a new one-pot synthesis consisting of in situ polymerization of pyrrole in the presence of structure guiding agent and CNF, and a two-step synthesis, in which CNF and PPy-NT were physically blended. Films based on one-pot synthesis (PPy-NT/CNFin) exhibited higher conductivity than those processed by physical blending, which was further enhanced up to 14.51 S cm-1 after redoping using HCl post-treatment. PPy-NT/CNFin containing the lowest PPy-NT loading (40 wt%), thus the lowest conductivity (5.1 S cm-1), displayed the highest shielding effectiveness of -23.6 dB (>90 % attenuation), thanks to the good balance between its mechanical properties and electrical conductivity.