Preparation of End-Capped Hyperbranched Polyaniline@Carbon Nanotube Hybrids for High-k Composites with Extremely Low Percolation Threshold and Dielectric Loss

How to greatly decrease the dielectric loss while maintaining extremely low percolation threshold (f(c)) is the main target of developing high-k conductor/polymer composites. Here, novel hybridized multiwalled carbon nanotubes (MWCNTs) with coated end-capped hyperbranched polyaniline (EHSiPA), EHSiPA@MWCNT, were developed and embodied into epoxy (EP) resin to produce new high-k composites. Systematic investigations of the structure and dielectric properties showed that the f(c) of EHSiPA@MWCNT/EP composites is as low as 0.41 wt %; in addition, EHSiPA@MWCNT/EP composites with suitable loadings of EHSiPA have much higher dielectric constants and lower dielectric losses than the MWCNT/EP composite. Specifically, the dielectric constant and loss at 100 Hz for EHSiPA3@MWCNT0.4/EP are 1.4 and 6.8 x 10(-3) times the values for the MWCNT0.4/EP composite, respectively. To reveal the origin of this, the distributions of space charges of EHSiPA@MWCNT/EP composites are discussed. This investigation suggests that designing and preparing new conductors with unique structures may provide a way to fabricate high-k composites.