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

Abstract

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.