Dielectric Properties of Polypropylene-Based Nanocomposites with Ionic Liquid-Functionalized Multiwalled Carbon Nanotubes

摘要

Nanocomposites were prepared from polypropylene (PP) and untreated multiwalled carbon nanotubes (MWCNTs) or MWCNTs surface-functionalized with ionic liquids (MIL), as fillers, and their dielectric properties were compared. The physical (cation-π/π-π) interaction between the ionic liquids and the MWCNTs was apparent from Raman spectroscopy and from thermo-gravimetric analysis. Morphology characterization revealed that ionic liquids improve the dispersibility of MWCNTs in the PP matrix. It is suggested that the substantial increase in the dielectric permittivity of the nanocomposites compared with that of the PP originates from a remarkable Maxwell-Wagner-Sillars (MWS) effect at percolation threshold where mobile charge carriers are blocked at internal interfaces between the MIL and the PP matrix. The high polarity of ionic liquids may reinforce the MWS effect, and the nonconducting organic groups of the ionic liquids promote the low loss tangent and low conductivity of the MIL/PP nanocomposites. Compared with MWCNTs/PP nanocomposites, lower loss tangent and higher dielectric permittivity were observed for MIL/PP nanocomposites, making the material more attractive for application in electronics.