Strong and electrically conductive nanopaper from cellulose nanofibers and polypyrrole

• Homogeneous coating of polypyrrole on cellulose nanostructure.
• Flexible and strong cellulose nanopaper with electrical activity.
• Nanopaper with 5.2 10−2 S cm−1 conductivity and 7.4 F g−1 specific capacitance.

In this work, we prepare cellulose nanopapers of high mechanical performance and with the electrical conductivity of a semiconductor. Cellulose nanofibers (CNF) from bleached softwood pulp were coated with polypyrrole (PPy) via in situ chemical polymerization, in presence of iron chloride (III) as oxidant agent. The structure and morphology of nanopapers were studied, as well as their thermal, mechanical and conductive properties. Nanopaper from pure CNF exhibited a very high tensile response (224 MPa tensile strength and 14.5 GPa elastic modulus). The addition of up to maximum 20% of polypyrrole gave CNF/PPy nanopapers of high flexibility and still good mechanical properties (94 MPa strength and 8.8 GPa modulus). The electrical conductivity of the resulting CNF/PPy nanopaper was of 5.2 10−2 S cm−1, with a specific capacitance of 7.4 F g−1. The final materials are strong and conductive nanopapers that can find application as biodegradable flexible thin-film transistor (TFT) or as flexible biosensor.

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