Sustainable high capacitance at high frequencies: Metallic aluminum-polypropylene nanocomposites

Lisa A. Fredin, Zhong Li, Michael T. Lanagan, Mark A. Ratner, Tobin J. Marks

Research output: Contribution to journalArticle

29 Citations (Scopus)

Abstract

The high-frequency dielectric response of 0-3 polypropylene nanocomposites prepared with the activated metallocene polymerization catalyst [rac-ethylenebisindenyl]zirconium dichlororide absorbed on the native Al 2O3 surfaces of metallic aluminum nanoparticles is characterized. The nanocomposites produced are randomly dispersed in the polyolefin matrix with no visible defects that might degrade film dielectric properties. Electrical measurements show that as the volume fraction of Al nanoparticles is increased, the effective permittivity of the nanocomposites increases, with εr values reaching ∼10 at relatively low frequency (1 MHz). Because of the high permittivity and conductivity contrast between the metal nanoparticles and the polypropylene matrix, Maxwell-Wagner-Sillars theory can be applied to model the loss at high frequencies and provide insight into how the nanocomposite high frequency response scales with Al volume fraction. At higher Al nanoparticle volume fractions, mixing theories predict greater densities of nanoparticle aggregates, consistent with the experimentally observed shift of the dielectric relaxation to lower frequencies. Although these nanocomposites undergo the predicted initial dielectric relaxation with increasing frequency, the metallic nanoparticle complex permittivity imbues the higher Al volume fraction materials with relatively high, sustainable permittivities, 6, at frequencies as high as 7 GHz.

Original languageEnglish
Pages (from-to)396-407
Number of pages12
JournalACS nano
Volume7
Issue number1
DOIs
Publication statusPublished - Jan 22 2013

Keywords

  • dielectric loss
  • dielectric materials
  • frequency response
  • inhomogeneous media
  • metal-insulator structures
  • metallic nanoparticle
  • nanocomposite

ASJC Scopus subject areas

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)

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