Flexible cellulose nanofibril/pristine graphene nanocomposite films with high electrical conductivity

Cellulose nanofibrils extracted from wood are natural polymer nanomaterials with high specific surface area, low density, high strength , and high elastic modulus . However, they are insulating materials and cannot be directly used in the electronic devices. Herein, pristine graphene (PG) exfoliated by triethanolamine was used to composite with TEMPO-oxidized cellulose nanofibril (TOCN) to prepare the conductive nanocomposite films in aqueous system. As a reference, the graphene oxide (GO) and reduced graphene oxide (RGO) were also composited with TOCN to prepared the TOCN−GO and TOCN−RGO composite films . The maximum electrical conductivity of the TOCN−PG film was 568 S/cm with 20 wt% PG, achieving great enhancement than the TOCN film with insulation. It was also much higher than the TOCN−GO films (3.44 × 10 −11  S/cm) and about 185 times more than TOCN−RGO composite films (3.06 S/cm). Moreover, the TOCN−PG composites containing 10 wt% PG exhibited excellent tensile strength , elastic modulus and the elongation at break of 389 MPa, 8.0 GPa and about 20%, respectively, much higher than those of the neat TOCN film.