Facile preparation of asymmetric Ni/PVC film with controlled structure: Application as a high-performance EMI shielding material

ABSTRACT Controlling the spatial configuration of conductive fillers in thin composites by a facile strategy is critical to widely commercial use these materials for electromagnetic interference (EMI) shielding applications. In this work, a series of free‐standing thin Ni/polyvinyl chloride (PVC) films with the same composition just systematically varied Ni particles dispersion states was prepared by solution casting method. The relationships between the structure and properties were also investigated. Ni particles motion was governed by evaporation and sedimentation during solvent evaporation with the presence of soluble PVC influencing the casting solution viscosity. The experimental results fit the 1D model. In dilute casting system, the effective concentration of Ni particles in the lower part of the film was significantly enhanced and a dense, closed packed conductive network was formed. This special distribution of Ni particles was found to play a key role in the corresponding properties. Compared to the uniform film, the film which was fabricated from the casting solution containing 0.03 g/mL PVC, exhibited much better electrical conductivity and EMI shielding performance. Furthermore, the detailed study shows that the obtained thin film exhibited excellent EMI SE values per unit film thickness of 200 dB/mm. Meanwhile, the resultant films possessed thermal conductivity of 0.32∼0.59 W/(m·K) depended on whether a Ni continuous network formation throughout the whole film in the temperature range of 30∼60°C. Our study results pave thus the way for scalable fabrication of substrate‐free systems that have advantages in multifunctional complex devices. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42560.