Polyaniline/Carbon black nanocomposites: The role of synthesis conditions on the morphology and properties

Abstract

The Polyaniline/Carbon black (PANI/CB) nanocomposites morphology and properties are extremely sensitive to the chemical synthesis conditions. This was observed when the structures obtained changed from globular-like to a multitude of globular-like and nanofiber structures by varying the aniline and CB concentration. The High-Resolution Transmission electron microscopy results showed that the globular-like structures consist of multi-core structures formed by CB particles covered by PANI. However, by increasing the monomer and CB concentration, while the monomer to CB mass weight ratio was kept constant, a PANI nanofibers network was also observed despite the formation of multi-core structures. These results suggest that PANI nucleation and growth processes proceed in two different ways, a homogenous nucleation and growth processes in the bulk solution and heterogeneous nucleation and growth processes at the CB surface. X-ray photoelectron spectroscopy (XPS) analysis showed that the in situ polymerization of aniline with the presence of CB may lead to the formation of PANI with higher degree of oxidation and higher degree of protonation. The hydrogen links from protonation may effectively stabilize the multi-core and nanofiber PANI network. Thermogravimetric analysis and differential scanning calorimetry results showed that the multi-core structure enhances the thermal stability of PANI/CB when compared to PANI.