Self-Assembled Conductive Network of Carbon Nanotubes-Polyaniline as Potential Nanocomposites

ABSTRACT

Carbon nanotubes are of great interest because of unique physical (mechanical, electrical, thermal, and chemical) properties. Especially their large elastic modulus and breaking strength make them highly attractive for their use as reinforced agents for traditional as well as conductive polymers forming a new class of multifunctional advanced carbon composites-nanocomposites. This is in addition to high electrical conductivity achieved through lower percolation thresholds for multitude of applications. Polyaniline (PANI) has a high potential due to its ease of synthesis, excellent environmental and thermal stability and reversible control of its electrical properties. A variant of PANI doped with DNNSA (dinonyl napththalene sulfonic acid) facilitates more promise by making it soluble and easily processable. In this work, DNNSA-PANI is used as a matrix for both the single- and multiwalled carbon nanotubes as nanoscale reinforced agents. The films were prepared with varying nanotube contents synthesized by spin-cast preceded by ultrasonic mixing of the constituents for a few hours. They were characterized using complementary analytical tools include scanning electron microscopy, atomic force microscopy, X-Ray diffraction, visible micro-Raman spectroscopy and room temperature dc electrical conductivity. These techniques reveal their morphology and microscopic structure and physical properties that help to establish process-microstructure-property relationship. The resulting nanocomposites possess enhanced or new sets of physical properties. However, because of occasional presence of inhomogeneities, the interfacial interactions and physical properties are ‘site-selective’ revealed using Raman spectroscopy ascribed to the charge transfer. The present work also discusses some of the findings in light of self-alignment of nanotubes in polymer matrix and their optical and electrical properties keeping in view of their applications ranging printable organic electronic and sensor devices, electrodes for fuel cell and high-energy density Li batteries, biosensing platform, space and naval uses.