Unifying Electromagnetic Shielding, Heat Dissipation, and Flexibility in Poly(vinyl alcohol) Composite Films by Designing a Hybrid Heterostructure

Developing flexible electronic devices and highly integrated electronic systems has imposed more stringent requirements on polymer-based composite films that can simultaneously exhibit excellent mechanical properties, thermal management, and effective electromagnetic interference (EMI) shielding. In this study, multiphase composite films were fabricated using Poly(vinyl alcohol) (PVA) as the matrix, while carbon nanospheres (CNs) prepared with Pluronic P123, Pluronic F108, and Pluronic F127 as structure-directing agents and niobium phosphide (NbP) were incorporated into the PVA system. The results showed that the PVA/NbP/F127C (PNF 127 ) composite film exhibited a tensile strength of 42.30 MPa, a tensile modulus of 0.25 GPa, an elongation at break of 139.01%, and a tensile toughness of 51.83 MJ·m –3 . Meanwhile, the PNF 127 composite film showed an in-plane thermal conductivity (TC) of 1.72 W·m –1 ·K –1 demonstrating distinct thermal anisotropy arising from continuous thermal conduction networks and efficient heat-transfer nodes. The PNF 127 composite film achieved stable shielding performance across the tested frequency range, with a total EMI shielding effectiveness of 39.40 dB. This study provides design insights into multicomponent synergistic strategies for multifunctional composite films in flexible electronics and electromagnetic protection applications.