RGO/CNTs heterogeneous interface modified by polyelectrolyte towards modulating negative permittivity of meta-composites

Abstract

Poly (sodium 4-styrene sulfonate) (PSS) and polyethyleneimine (PEI) were firstly assembled on the reduced graphene oxide (rGO) surface to control negative permittivity properties through regulating heterogeneous interface of rGO/carbon nanotubes (CNTs) in meta-composites. The rGO/CNTs/cellulose composite films obtained negative permittivity while the carbon content was 30 wt%. After the rGO/CNT interface was modified by PSS, it was found that the negative permittivity was also observed even though the carbon content was only 20 wt%. The strong electron-absorbing character of sulfonic acid groups and large benzene rings in the PSS molecule chain, played an important influence on the properties of the rGO/CNT heterogeneous interface, resulting in the controllable negative dielectric properties. The obtained negative permittivity was perfectly fitted by Lorentz and/or Drude models. However, after obtaining the rGO-PEI-CNTs interface, PEI with the positively charged protonated amino groups neutralized the negative charges and deteriorated the dispersion of rGO and CNTs, leading to the decrease in dielectric loss and the shift from negative to positive permittivity. The connection between reactance and permittivity was demonstrated by an equivalent circuit analysis of the impedance response. This work offered a new approach to controlling negative permittivity via micro-interface regulation engineering in full depth.