Nonlinear conduction and multifunctional integration enabled by segregated network modulation in PET@Ni composites

Abstract

Achieving tunable, high-performance electrical and electromagnetic properties in polymer-based composites remains challenging due to insufficient understanding of the relation between particle structure, surface conduction, and internal tunneling in segregated networks. Here, a multi-scale strategy is presented to elucidate and optimize the electrical conduction mechanisms in nickel-coated polyethylene terephthalate (PET@Ni) composite films with segregated network systems. Composite films with controlled particle size and tailored Ni shell thickness were fabricated via electroless plating and sequential hot pressing. The conductive network architecture governed transport behaviors. Surface conduction dominated in thin films, while interparticle tunneling dominated in thick configurations. A multi-level theoretical model was developed. Relaxation dynamics and quantum mechanical corrections based on density functional theory were incorporated. The proposed model describes the observed conductivity behaviors with high accuracy (R² > 0.98). Finite element simulations further confirmed the spatially heterogeneous current densities and electric field intensities. Microcapacitive behavior was enhanced in films with smaller particles due to increased Ni shell connectivity. Dual-layer structures provided additional tunability. Secondary Ni plating boosted electromagnetic interference (EMI) shielding up to 63.77 dB. A robust structure-property framework was established. These results offer new design principles for scalable, multifunctional polymer-based composites in advanced electronics, EMI shielding, and next-generation sensing systems.