Electromagnetic interference shielding of carbon nanotube-fluoropolymer elastomer composites with layered structure

Abstract

This paper presents carbon nanotubes-containing polymer composites with layered gradient structure having electromagnetic interference (EMI) shielding properties. Polymer composite films were obtained on metal surface by aerosol deposition of a dispersion of carbon nanotubes in the solution of a copolymer of vinylidene fluoride with hexafluoropropylene (SCF-26) in acetone. Single-wall TUBALL (OCSiAl) carbon nanotubes were used. Three-layer coatings were formed with a concentration of nanotubes decreasing in each subsequent deposited layer. The reflection coefficient of electromagnetic radiation in the range of 20–35 GHz was measured. Gradient samples had significantly better characteristics compared to samples with uniform concentration of carbon nanotubes: the reflection coefficient reached −6dB at 35 GHz. The outer layer of gradient structure with 0.1 wt % CNT provides a better matching of the wave resistance with free space and a smooth entrance of an electromagnetic wave into the sample. The subsequent layers with an increasing concentration of single-walled carbon nanotubes (0.3 and 0.5%) absorb electromagnetic radiation. Polymer elastomer composite EMI shielding coatings with concentration gradient can be applied by aerosol deposition to the surfaces of any composition and shape. Our results could serve as a design tool in carbon nanotubes - based EMI shielding flexible polymer coatings.