Interface-engineered core–shell nanoparticle embedded polymer nanocomposite demonstrating low voltage and temperature dependent tunable dielectric response

Abstract

Ferroelectric polymer composites with nonlinear dielectric properties are promising candidates for flexible electronics and microwave systems. However, their high-bias field requirements hinder broader applicability. Here, we report a low-voltage tunable nanocomposite comprising (3-aminopropyl)triethoxysilane (APTES)-functionalized core–shell nanoparticles with a Barium Strontium Titanate (BST) core and ZnO shell, embedded in a poly(vinylidene fluoride-tetrafluoroethylene) (P(VDF-TrFE)) matrix. The synergistic combination of high-k BST and intrinsically nonlinear ZnO enables a dielectric tunability (T_u) of 12.27% at 6.67 kV mm⁻¹, four times higher than BST/P(VDF-TrFE) counterpart (3.09%). APTES functionalization enhances filler–matrix interfacial compatibility and suppresses the dielectric loss (tan δ) from 0.123 to 0.038 (3.24 times) at 100 Hz. Notably, the nanocomposites exhibit a rare temperature-dependent transition in the T_u curve, transitioning from negative to positive T_u with a switching temperature of 20 °C (close to room temperature) for the APTES functionalized system. This study introduces a viable route to engineer low-voltage, temperature-adaptive dielectric materials for next-generation tunable microwave and RF device applications.