Development of functionalised multiwalled carbon nanotube polyaniline composites for electrical applications

Abstract

Combining intrinsically conducting polymers with carbon nanotubes newline(CNT) helps in creating composites with superior electrical and thermal newlinecharacteristics. These composites are capable of replacing metals and newlinesemiconductors as they possess unique combination of electrical conductivity, newlineflexibility, stretchability, softness and bio-compatibility. Their potential newlinefor use in various organic devices such as super capacitors, printable newlineconductors, optoelectronic devices, sensors, actuators, electrochemical newlinedevices, electromagnetic interference shielding, field effect transistors, newlineLEDs, thermoelectrics etc. makes them excellent substitutes for present day newlinesemiconductors. newlineHowever, many of these potential applications have not been fully newlineexploited because of various open ended challenges. Composites meant for newlineuse in organic devices require highly stable conductivity for the longevity of newlinethe devices. CNT when incorporated at specific proportions, and with newlinespecial methods contributes quite positively to this end. newlineThe increasing demand for energy and depleting fossil fuel reserves newlinehas broadened the scope for research into alternative energy sources. A newlineunique and efficient method for harnessing energy is thermoelectric energy newlineconversion method. Here, heat is converted directly into electricity using a newlineclass of materials known as thermoelectric materials. Though polymers have newlinelow electrical conductivity and thermo power, their low thermal conductivity newlinefavours use as a thermoelectric material. The thermally disconnected, but newlineelectrically connected carrier pathways in CNT/Polymer composites can satisfy the so-called phonon-glass/electron-crystal property required for newlinethermoelectric materials. newlineStrain sensing is commonly used for monitoring in engineering, newlinemedicine, space or ocean research. Polymeric composites are ideal candidates newlinefor the manufacture of strain sensors. Conducting elastomeric composites newlinecontaining CNT are widely used for this application. These CNT/Polymer newlinecomposites offer resistance change over a large strain range due to the low newlineYoungand#8223;s modulus and higher elasticity. They are also capable of covering newlinesurfaces with arbitrary curvatures. newlineDue to the high operating frequency and bandwidth of electronic newlineequipments electromagnetic interference (EMI) has attained the tag of an newline environmental pollutantand#8223;, affecting other electronic devices as well as newlineliving organisms. Among the EMI shielding materials, polymer composites newlinebased on carbon nanotubes show great promise. High strength and stiffness, newlineextremely high aspect ratio, and good electrical conductivity of CNT make newlineit a filler of choice for shielding applications. A method for better dispersion, newlineorientation and connectivity of the CNT in polymer matrix is required to newlineenhance conductivity and EMI shielding. newlineThis thesis presents a detailed study on the synthesis of functionalised newlinemultiwalled carbon nanotube/polyaniline composites and their application newlinein electronic devices. The major areas focused include DC conductivity newlineretention at high temperature, thermoelectric, strain sensing and electromagnetic newlineinterference shielding properties, thermogravimetric, dynamic mechanical newlineand tensile analysis in addition to structural and morphological studies. newline