Flexible polyethylene terephthalate/polyaniline composite paper with bending durability and effective electromagnetic shielding performance

Abstract

With rapid advances in smart, wearable electronic devices, the creation of flexible electromagnetic interference (EMI) shielding materials with high-performance is an important prerequisite. However, the synthesis of flexible polyaniline (PANI) paper with excellent bending durability remains a significant challenge because of the inherently rigid nature of its polymer chains. This study presents a flexible freestanding PANI-based composite paper with effective EMI shielding capability and robust bending durability. Polyethylene terephthalate (PET) paper with a porous structure was selected as a framework. Then, a thin PANI coating was successfully intertwined on PET fibers by a facile in-situ polymerization strategy. An effective shielding performance of up to 23.95 dB was achieved at a thickness of only 0.29 mm. Long-term cycle testing of bending deformation demonstrated that EMI shielding remained at 99.0% even after 10,000 deformation cycles. This durability far surpasses all previously reported flexible shields. The excellent durability is attributed to the porous structure, strong interfacial interaction between the PET fiber and PANI layer, and an appropriate PANI coating thickness. The correlation between the reaction condition and the electromagnetic characteristics is extensively investigated. The attenuation constant, skin depth analysis, and a comparison of experimental results and theoretical predictions reveal the underlying shielding mechanisms. The efficient multiple reflections occurring within the same or adjacent PET/PANI fibers make a significant contribution to absorption loss. Therefore, the attenuation of microwaves is mainly controlled by the absorption mechanism. Furthermore, the PET/PANI composite paper with an effective EMI shielding capability can provide relevant models for studying flexible shields. It is firmly believed that such a shielding material will meet the expectations for advanced, flexible, smart electronic devices.