In this paper, reinforcement of dielectric nanocomposite was performed for polyvinyl fluoride (PVDF) as a matrix, which is a practical requirement for foldable and flexible electric energy devices. A fibrous nanofiller, 2,2,6,6-Tetramethylpiperidine 1-oxyl (TEMPO)-oxidized cellulose nanofiber (TOCN) was employed as a nanofiller for the PVDF nanocomposite incorporating highly dielectric barium titanate nanoparticles (BT NPs). Prior to the fabrication of nanocomposite films, a chemical treatment by HCl and a surface-modification with trifluoropropyl group were applied to TOCN and BT nanoparticles, respectively. Their treatments brought about both nanofillers well-dispersed in a polar aprotic solvent for PVDF. A low percentage incorporation of the treated TOCNs up to 0.5 wt% was found to be sufficient for enhancement on the mechanical strength of nanocomposites at a high content of surface-modified BT NPs (30 vol%). The permittivity of the nanocomposites was in the range of 12 to 14 that is twice higher than that in the PVDF film. The PVDF nanocomposites at the treated TOCN loading of 0.3 to 0.5 wt% exhibited superior mechanical strength to the PVDF film. The ternary combination of PVDF, the treated TOCN, and the surface-modified BT NPs showed an improvement on tensile stiffness with maintaining the intrinsic high dielectric properties of nanocomposite films. The present nanocomposite can be a promising ternary system for an advanced design of polymer dielectrics with excellent energy storage properties.
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