Electrical and Thermoelectric Properties of Functionalized Multiwalled Carbon Nanotube/Polyaniline Composites Prepared by Different Methods

Nanocomposites consisting of functionalized multiwalled carbon nanotubes and polyaniline (PANI) were prepared by traditional in-situ polymerization and dynamic interfacial polymerization methods. Morphological and structural analysis showed that synthesis by interfacial polymerization resulted in a well-ordered composite with a uniform core-shell structure, while traditional in-situ dynamic polymerization resulted in composites having a thick core shell structure with many protrusions. Composites synthesized by interfacial polymerization showed better electrical conductivity and seebeck coefficient as compared to composites synthesized by traditional in-situ polymerization. The highly extended and well-aligned PANI chain structure increased the effective degree of electron delocalization between pi bonds in aromatic rings of PANI and graphitic structure of nanotubes and, therefore, enhanced the carrier mobility in PANI. However, there was no corresponding increase in the thermal conductivity of the composite, which was due to phonon scattering effect of nanointerfaces. Thus, the introduction of a large number of nanointerfaces, which scatter phonons very effectively, leads to the development of nanostructured composites with enhanced power factor making it suitable for thermoelectric applications.