Effect of surface modification on the dielectric properties of PEN nanocomposites based on double-layer core/shell-structured BaTiO3 nanoparticles

摘要

Novel polymer nanocomposites were prepared by employing double-layer core/shell-structured BaTiO_3 nanoparticles as fillers and polyarylene ether nitrile (PEN) as the polymer matrix. The BaTiO_3 nanoparticles were surface amine-functionalized by a silane coupling agent, and then grafted by hyperbranched copper phthalocyanine (HBCuPc) to modify their surface chemical activations. It was found to be an effective method to derive reactive functional groups on the nanoparticles surface from TEM and FTIR analyses. The SEM images showed that the interfacial properties of PEN nanocomposites were greatly improved through surface chemical modification of BaTiO_3 nanoparticles, though the dielectric constant decreased by 16% due to the surface passivation effect from modification shells. Furthermore, the dielectric properties of PEN nanocomposites were measured as a function of both frequency and temperature. The results indicated that the PEN nanocomposites show an extreme insensitivity to negative temperature and a strong sensitivity to high temperature (around the glass transition temperature), which is consistent with the theory of molecular motion. Thus, surface modification can effectively tailor the nanoparticles surface chemical activations and optimize the material interfacial properties, but also can reduce the loss tangent, thereby improving the quality of dielectric materials.