Negative Permittivity Behavior in Flexible Carbon Nanofibers- Polydimethylsiloxane Films

Haikun Wu, 1, 2

Haowei Sun, 1

Fengjin Han,1

Peitao Xie, 1*Email

Yiming Zhong, 1

Bin Quan,3

Yaman Zhao, 4

Chunzhao Liu, 1*Email

Runhua Fan4 

Zhanhu Guo 5

1State Key Laboratory of Bio-fbers and Eco-textiles Institute of Biochemical Engineering, College of Materials Science and Engineering, Qingdao University, Qingdao 266071, China

2 Hong Kong Branch of National Precious Metals Material Engineering Research Centre (NPMM), Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong, China

3 Institute of Advanced Materials and Flexible Electronics (IAMFE), School of Chemistry and Materials Science, Nanjing University of Information Science & Technology Nanjing 210044, China

4 College of Ocean Science and Engineering, Shanghai Maritime University, Shanghai,China

5 Integrated Composites Laboratory (ICL), Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States

Abstract

Flexible electronic devices have recently become a research hotspot due to their potentials 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 polydimethylsiloxane (PDMS) matrix is designed to construct the flexible metamaterials with negative permittivity, showing excellent mechanical durability and flexibility. The microstructures, mechanical durability, alternating current conductivity (σac) and permittivity (ɛ′ and ɛ") 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 conductive CNFs network. The equivalent circuit models were used to analyze 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.

Negative Permittivity Behavior in Flexible Carbon Nanofibers- Polydimethylsiloxane Films