Effect of directly added coupling agent on the dielectric properties of ceramic-polymer nanocomposites

In this work, the 3-Aminopropyltriethoxysilane was directly added as coupling agent during the fabrication process of BaTiO₃-P(VDF-CTFE) nanocomposites through solution-casting, in order to develop an easy, low-cost, and widely applicable method to improve the compatibility of binary composite system. It was experimentally found that the dielectric constant and energy storage density of the nanocomposite were enhanced by the addition of a small amount of coupling agent, which was attributed to the improvement of wettability between fillers and matrix. For the composites with the addition of a large amount of coupling agent, the aggregation of fillers and formation of polymer blends lead to a lower ε_r, higher tanδ, and smaller U_discharge. It was also identified that the glass transition behavior of polymer matrix was influenced by the addition; therefore, the temperature dependence of dielectric properties was modified. As a result of the improved compatibility and enhanced dielectric properties, a maximal discharge energy storage density of 3.4 J/cm³ was achieved from the nanocomposites with 5 vol.% fillers and 1 wt.% coupling agent.