Enhancing the performance of ▫$BaTi_{0.89}S_{0.11}O_3$▫/ PVDF‑HFP composites through tailored functionalization of barium stannate titanate ▫$(BaTi_{0.89}S_{0.11}O_3)$▫ fillersZahid, Marwa (Avtor) Amjoud, M'barek (Avtor) Mezzane, Daoud (Avtor) El Marssi, Mimoun (Avtor) Uršič Nemevšek, Hana (Avtor) Goričan, Ivana (Avtor) Kmet, Brigita (Avtor) Kutnjak, Zdravko (Avtor) Gouné, Mohamed (Avtor) nanocompositesinterfacial functionalizationpiezoelectric propertiesdielectric propertiesNanocomposites are currently attracting significant attention in the energy sector, particularly for storage applications. However, controlling interfacial compatibility remains a challenge. This work introduces a novel interfacial functionalization strategy that enables the achievement of exceptional dielectric properties and addresses the persistent issue of poor filler–matrix interaction in nanocomposites. A poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) matrix was filled with lead-free BaTi0.89Sn0.11O3 (BTS11) nanoparticles, which exhibit ultra-high piezoelectric performance near ambient temperature. These nanoparticles were functionalized with various modifying agents, including ethylenediamine (EDA), polyvinylpyrrolidone (PVP), polydopamine (PDA), and 3-aminopropyltriethoxysilane (APS). The study demonstrated that the functionalized HO-BTS11@modifier/PVDF-HFP nanocomposites exhibit distinct dielectric characteristics depending on the modifying agent. The HO-BTS11@EDA/PVDF-HFP nanocomposites, which included hydroxylated HO-BTS11 nanoparticles modified with EDA, outperformed other modified systems with the maximum energy storage efficiency (~ 77%) and a dielectric permittivity of 70 at 1 kHz. EDA with small molecular size, low polarity, and ability to form hydrogen bonds enable improved interfacial adhesion with the hydrophobic PVDF-HFP matrix making the composite suitable for enhancing energy storage performance. This selective functionalization strategy not only provides new insights into interface engineering but also offers a promising pathway for the development of high-performance materials for energy storage and harvesting devices, embedded capacitors, flexible electronics, and next-generation dielectric systems.Springer Nature20252026-01-19 11:22:58Neznano25376ZDAsl