Functionalization of BaTiO3 Nanoparticles to Optimize the Dielectric Performance of Electroactive Polymer Nanocomposites Based on PDMS Matrix

The growing demand for portable and wireless electronic devices, along with the necessity to reduce reliance on non-renewable energy sources, has driven the need for energy harvesting materials. Nanocomposites, combining a polymeric matrix and a high-performance dielectric ceramic phase, are a promising solution. In such systems, the design of a hybrid matrix–filler interface is critical for achieving desired properties. Here, nanocomposites (NCs) were prepared by adding various amounts of hydrothermally synthesized BaTiO3 (BT) nanoparticles (NPs) to polydimethysiloxane (PDMS). To investigate hybrid interfaces, NPs were used either bare or surface-functionalized with two silanes, 3-glycidyloxypropyltrimethoxysilane (GPTMS) or 2-[acetoxy(polyethyleneoxy)propyl]triethoxysilane (APEOPTES). NC films (80–100 μm thick) were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDXS), and thermogravimetric analysis (TGA). Dielectric properties and breakdown strength (EBD) were measured, and the theoretical volumetric energy density was calculated as a function of the filler loading and functionalization. The results demonstrate that hybrid interface design is pivotal for enhancing dielectric performance in NCs. APEOPTES-functionalized NPs significantly improved the dielectric response at a low filler loading (3.5%vol.), increasing permittivity from 2.8 to 7.5, EBD from 33.8 to 42.1 kV/mm and energy density from 30 to >100 mJ/cm3. These findings underscore that designing hybrid interfaces through NP functionalization provides an effective strategy to achieve superior dielectric performance in PDMS-based NCs, retaining the advantages of the elastomeric matrix by reducing the amount of ceramic fillers.