Tailoring the Electrical Response of Polyvinylidene Fluoride Nanocomposites with Electrically Conductive and Dielectric Fillers

Polymer-based composites combining the flexibility, low density, and processability of the matrix with the tailored functional performance provided by the fillers are also particularly suitable for large area, flexible, and printable applications. Herein, polyvinylidene fluoride (PVDF) composites with conductive graphene nanoplatelets (G-NPL) and high-dielectric constant ceramics, including barium and strontium titanate (BT and SrT), have been developed to achieve electrically conductive and high-dielectric response materials, respectively. Flexible composites reinforced with 45 wt% ceramic content lead to a dielectric constant of epsilon ' = 33 and 25 for BT and SrT, respectively, 6 and 4 times higher than for pristine PVDF. Further, the inclusion of G-NPL allows for the development of highly conductive composites with a maximum conductivity of 5.5 x 10-2 (omega.m)-1 for a 5 wt% filler content, 10 orders of magnitude larger than PVDF. The G-NPL and ceramic in optimized contents in PVDF tricomposites do not enhance the dielectric properties compared to PVDF-ceramic composites. Theoretical analysis has been used to determine the critical percolation threshold of the PVDF/G-NPL, which occurs at phi c=$\left(\phi\right)_{\text{c}} =$0.6 wt% G-NPL content with a critical exponent of t = 2.49 and to describe the dielectric properties of the composites, allowing to further tailor materials responses for specific application needs. High-dielectric composites using polyvinylidene fluoride (PVDF) as matrix and strontium titanate or barium (BT) as reinforcement materials are done for 30 and 45 wt% filler contents without abruptly increasing their losses. A dielectric constant larger than 30 for the 45BT/PVDF composite is achieved, demonstrating a homogeneous dispersion of BT in the PVDF matrix. A theoretical model is performed, showing excellent fitting behavior.image (c) 2023 WILEY-VCH GmbH