Three‐phase interfacial design in BaTiO ₃ / rGO /polyetherimide composite enabling enhanced dielectric, thermal and mechanical properties

Abstract As core components in electric/electronic fields, dielectric materials have recently received ever‐increasing interests. Among them, polymer‐based dielectric composites have drawn ever‐increasing attentions due to their high‐temperature resistance and excellent processibility. However, state‐of‐art studies mostly focus on the modification of single‐phase filler, while the heterogeneous three phase interactions between fillers and polymer matrix are rarely studied. To fill this gap, in this study, a novel strategy of interfacial design and structural construction of three‐phase BaTiO ₃ /rGO/polymer nanocomposites have been promoted to simultaneously build interfacial barriers between adjacent rGO nanosheets and to enhance the interfacial polarization of rGO nanosheets for improved dielectric, thermal and mechanical properties. The dielectric constant of 0.6 wt% BT/ARGO/PEI reached 644@1 kHz with a dielectric loss of only 0.218, while these values for 0.5 wt% ARGO/PEI composites are 471 and 0.489, respectively. Meanwhile, the breakdown strength almost doubled (from 48 kV·mm ⁻¹ to 87 kV·mm ⁻¹ ) upon the addition of BaTiO ₃ (BT) nanoparticles. Moreover, the introduced BT nanoparticles significantly enhanced the intermolecular frictions between different materials and contributed largely to promoted mechanical and thermal properties. We therefore speculate this work establishes a strong foundation for fabricating three heterogeneous‐phase high dielectric polymer materials with excellent dielectric, thermal and mechanical properties. Highlights Graphene oxide was modified by APTES and reduced by L‐Ascorbic Acid. Three‐phase BT/ARGO/PEI composites showed enhanced dielectric properties. The incorporated BT nanoparticles reduced the dielectric loss. The thermal and mechanical properties of BT/ARGO/PEI composites are optimized. Interfacial interactions between different phase of materials are studied.