Abstract: The interfaces between nanofillers and the polymer matrix in nanocomposites are known to be increasingly important when nanofillers become smaller. A P(VDF-TrFE-CFE) terpolymer is used as the template polymer matrix and low-K（dielectric constant） SiO2 and high-K BaTiO3 nanoparticles as fillers to determine the enhancement effect of the interfaces. For both kinds of fillers, anomalous increases in the dielectric constant and polarization response are observed at nanoparticle loading less than 1%( volume fraction). These increases are not related to the intrinsic dielectric properties of the nanofillers and the change of crystallinity of the terpolymer. The crystalline phase is slightly changed from a non-polar structure towards a more polar one, improving the dielectric response in the interfacial regions. An interfacial model is proposed and the non-uniform dielectric response of the interfacial regions is responsible for the observed dielectric phenomena. The overlapping of the interfacial regions leads to the maximum dielectric response of the nanocomposites with certain particle loading.

Key words: dielectric materials, nanocomposites, interfacial effect, terpolymer