Enhanced interfacial dielectric polarization in PVDF-HFP copolymer with treating PPy by using silane coupling agent

Abstract

Dielectric materials are polar materials for energy storage applications such as capacitors, transformer, and other electrical devices. The great dielectric properties generally depend on easily switchable polarization and higher-order structure in a material. Filler composite in the flexible dielectric polymer is then considered to rearrange polymer chain. However, the filler becomes agglomeration easily at high loading content in polymer, resulting in high energy loss and low electrical breakdown. This work presents the treated Polypyrrole (PPy) filler by 3-Aminopropyltriethoxysilane for avoiding agglomeration in PVDF-HFP thin film. These 30 μm PVDF-HFP film thickness is fabricated by tape casting method with N, N-dimethylformamide (DMF) solvent. The distributions of PPy filler on PVDF-HFP are observed by SEM image. Dielectric constant, dielectric loss, and conductivity are analyzed. As a result, the maximum silane content was found on 1 wt% for 1 wt% PPy/PVDF-HFP to maximized dielectric constant and reduce dielectric loss and conductivity. The conductive of PPy filler was lowered by covering with electrical insulating silane, resulting in decreased dielectric loss and conductivity. Then, polymer chain with silane bonding easily polarized under the electric field, resulting in an intensification of dielectric constant around 2.5 times compared with non-silane. Afterward, this dielectric constant clearly decreased when it reached to exceeded silane content as 5-20 wt%. Treated PPy with the suitable silane content in PVDF-HFP performs good dielectric properties for advanced energy storage in this work.