Structure and electrochemical properties of polystyrene/CNT nanocomposites

Abstract

The realization of the outstanding properties of CNTs (carbon nanotubes) is constrained by their inherent tendency to agglomerate. Emulsion polymerization was used for synthesizing poly(styrene)/CNT nanocomposites with functionalized CNTs. Chain transfer agents (CTAs) were incorporated to control polymer molar mass and end-use properties. Data from electrical impedance spectroscopy (EIS) at variable frequencies were analyzed to characterize and elucidate the electrical characteristics of poly(styrene) (PS)/CNT nanocomposites. The incorporation of CNT in the polymer matrix even at modest concentrations enhanced the electrical properties of the non-conductive poly(styrene) significantly as revealed by EIS spectra. The use of CTA enabled modulation of polymer molar mass and variation in the electrical properties for PS/CNT relative to composites with no CTA. The electrical behavior of PS/CNT dispersion has been shown to depend both on the CNT concentration and molecular weight of the substrate. The equivalent electrical circuit (EEC) analyses with the corresponding system parameters enabled determination of relative CNT arrangements for different types of PS/CNT composites. TEM images confirmed the CNT positions within the composites and helped support interpretation of EIS/EEC data.