Mechanical and Electrical Properties of Solution-Processed Polyaniline/Multiwalled Carbon Nanotube Composite Films

Abstract

Mechanical and electrical properties of high molecular weight polyaniline/multiwalled carbon nanotube composite films were investigated. Addition of carbon nanotubes to polyaniline films was accomplished by solution processing. Physical characterization of these composites by thermogravimetric analysis, tensile testing, dynamic thermal mechanical analysis, and atomic force microscopy measurements indicate that polyaniline containing 1% carbon nanotubes is more mechanically and thermally stable than neat polyaniline. Rectifying aluminum contacts were fabricated using this composition of the composite material, along with neat polyaniline for comparison. The measured electrical characteristics indicate that the current levels of the polyaniline/carbon nanotube composite devices are nearly an order of magnitude higher than those of the polyaniline devices; thus, this composite material has the potential for applications in organic electronics.There is considerable interest in using inherently conducting polymers ͑ICPs͒ in microelectronics. The potential for ICPs to provide lightweight, low cost, electronic, and photonic materials that can be produced by existing polymer processing techniques is highly attractive. Polyaniline ͑PANI͒ in particular has attracted significant interest due to its excellent thermal and environmental stability as compared to other conducting polymers. 1-4 Therefore, PANI holds great promise as a material for electronic device applications. 5-7 Despite substantial advances in the last 10 years in materials and processing techniques, the performance of devices based on conducting polymers remains inferior to inorganic devices. Some recent results indicate that PANI composite materials may have significantly improved electronic and mechanical properties as compared to neat PANI films, making the composite more suitable for microelectronic applications.PANI/carbon black composites have been studied by several groups. 8,9 Charge transport in PANI is normally explained in general by various hopping mechanisms. The addition of carbon black ͑CB͒ to the PANI matrix typically leads to an increase in highly ordered sites distributed in the polymer known as metallic islands, which subsequently increase the probability of charge transport between conjugated polymer chains. The overall effect of the CB addition is an increase in the conductivity of the material. 10 Another material of considerable interest for the fabrication of such composites is the carbon nanotube ͑CNT͒. One of the main advantages of CNTs over CB is that a low loading ͑ϳ1 wt %͒ of CNTs is sufficient for achieving composite properties comparable to that of a 10% CB loading. 11 The presence of higher CB content compromises the physical and mechanical properties of the composite. Furthermore, carbon nanotubes are essentially nanoscale fibers with a high aspect ratio and high conductivity. It is believed that nanoengineered conducting polymer composites could provide synergistic effects, whereby carbon nanotubes would enhance the thermal ...

Polyaniline-carbon nanotube composites

“…However, in the case of PANI-CNT films, the modulus decreases as the CNT content is increased, while the per cent strain increases from 12 % for neat PANI to 30 % for the composite with 1 % CNT. But the per cent strain decreases to 11 % for a 5 % CNT loading indicating that the composite films become more brittle when loaded in excess of 1 % CNT [90]. The dispersion of PANI-MWCNT composite with 1 wt % polyvinyl alcohol in insulating silicone oil behaves like an electrorheological fluid.…”

Thin-Film Organic Electronic Devices

“…Suitable matrices include the transparent and widely available poly(methyl methacrylate) and polystyrene. Polyaniline represents another possible matrix; in that case, percolation requires only a close approach of nanotubes, rather than direct contact, and even lower loading levels are possible (20,21). A polyaniline-nanotube composite with loading levels on the order of 1% was patterned by use of laser ablation-induced dry transfer to make conductive lines suitable for organic electronics (22).…”

Smart conducting polymer composites having zero temperature coefficient of resistance

“…[1][2][3][4][5] In particular, they are a practical choice of material in heat-related applications such as in 25 patternable micro heaters, temperature sensors, heating glasses for vehicles, thermoelectric devices, water heaters, and flexible de-icing units. [6][7][8][9] By the electric Joule heating (resistive heating) of conducting composites, electrical energy can be converted into heat energy easily and quantitatively.…”