Negative Permittivity Behavior in Flexible Carbon Nanofibers- Polydimethylsiloxane Films
Haikun Wu, Haowei Sun, Fengjin Han, Peitao Xie, Yiming Zhong, Bin Quan, Yaman Zhao, Chunzhao Liu, Runhua Fan, Zhanhu Guo
Abstract
Flexible electronic devices have recently become a research hotspot due to their potential in different applications. However, there is a lack of studies about flexible metamaterials with negative parameters. In this work, the composite film with carbon nanofibers (CNFs) dispersed in a polydimethylsiloxane (PDMS) matrix is designed to construct flexible metamaterials with negative permittivity, showing excellent mechanical durability and flexibility. The microstructures, mechanical durability, alternating current conductivity (ac), and permittivity ( and ") were investigated and discussed in detail. A transition of conduction mechanism from jumping conduction to metal-like conduction was observed when the CNFs content was improved from 6 to 14 wt%. The CNFs-PDMS film with CNFs content of 14 wt% achieved negative permittivity over the whole frequency, which resulted from the construction of a conductive CNFs network. The equivalent circuit models were used to analyze the impedance (Z and Z) behavior of the composites to determine the mechanism of negative permittivity. This study will provide theoretical and technical support for the design of flexible metamaterials and promote their practical applications in wearable electronic devices.