Improved Thermoelectric Behavior of Nanotube-Filled Polymer Composites with Poly(3,4-Ethylenedioxythiophene) Poly(Styrenesulfonate)

Department of Mechanical Engineering, Texas A&M University, College Station, Texas 77843, USA.
ACS Nano (Impact Factor: 12.88). 01/2010; 4(1):513-23. DOI: 10.1021/nn9013577
Source: PubMed

ABSTRACT The thermoelectric properties of carbon nanotube (CNT)-filled polymer composites can be enhanced by modifying junctions between CNTs using poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS), yielding high electrical conductivities (up tõ40000 S/m) without significantly altering thermopower (or Seebeck coefficient). This is because PEDOT:PSS particles are decorated on the surface of CNTs, electrically connecting junctions between CNTs. On the other hand, thermal transport remains comparable to typical polymeric materials due to the dissimilar bonding and vibrational spectra between CNT and PEDOT:PSS. This behavior is very different from that of typical semiconductors whose thermoelectric properties are strongly correlated. The decoupled thermoelectric properties, which is ideal for developing better thermoelectric materials, are believed to be due to thermally disconnected and electrically connected contact junctions between CNTs. Carrier transport at the junction is found to be strongly dependent on the type and concentration of stabilizers. The crucial role of stabilizers was revealed by characterizing transport characteristics of composites synthesized by electrically conducting PEDOT:PSS and insulating gum Arabic (GA) with 1:1-1:4 weight ratios of CNT to stabilizers. The influence of composite synthesis temperature and CNT-type and concentration on thermoelectric properties has also been studied. Single-walled (SW) CNT-filled composites dried at room temperature followed by 80 °C exhibited the best thermoelectric performance in this study. The highest thermoelectric figure of merit (ZT) in this study is estimated to bẽ0.02 at room temperature, which is at least one order of magnitude higher than most polymers and higher than that of bulk Si. Further studies with various polymers and nanoparticles with high thermoelectric performance may result in economical, lightweight, and efficient polymer thermoelectric materials.

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    • "For polymer-based thermoelectric materials to achieve a ZT that is comparable to that of inorganic thermoelectric materials, it is essential to enhance the Seebeck coefficient without decreasing the electrical conductivity. For this reason, numerous researchers have suggested organic/inorganic composites such as poly(3,4-ethylenedioxythiophene): poly(4-styrenesulfonate) (PEDOT:PSS)/carbon nanotubes (CNTs) [16], PEDOT:PSS/Te nanorods [19], PEDOT:PSS/Ca 3 Co 4 O 9 [20], PEDOT:PSS/ PbTe [21], PEDOT:PSS/Bi 2 Te 3 [7] [22], P 3 HT/Bi 2 Te 3 [25], and polyaniline (PANI)/CNTs [26] to achieve better thermoelectric performance. We herein suggest a quick, simple, and high-yielding synthesis method for preparing PEDOT:PSS/Ge composite films for use as thermoelectric "
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    ABSTRACT: We herein report on the enhanced thermoelectric properties of poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS)/Ge composite films fabricated by drop-casting of a solution of Ge powder in PEDOT:PSS. The power factor of the fabricated PEDOT:PSS/Ge composite films with 29.6 wt.% Ge was 165 μW m− 1K− 2, and they exhibited an extremely low thermal conductivity. The maximum thermoelectric figure of merit was anticipated to be ~ 0.1 at room temperature for the PEDOT:PSS/Ge composite films with 29.6 wt.% Ge, suggesting that their heterostructure was effective in enhancing their thermoelectric efficiency.
    Thin Solid Films 09/2014; 566:14–18. DOI:10.1016/j.tsf.2014.07.011 · 2.13 Impact Factor
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    • "Carbon nanotubes (CNTs), consisting of graphitic sheets rolled up into a cylindrical shape, are often used as templates in such syntheses [10] [11]. Up to now, several synthetic procedures have been reported for the synthesis of PEDOT/CNTs nanocomposites, such as the solid state mixing of both powder components, the mixture of dispersions of each component [12], the electrochemical polymerization of 3,4-ethylenedioxythiophene (EDOT) over a CNTs-based electrode [13] and in situ chemical polymerization of EDOT in CNTs suspensions [14]. However, these routes generally yielded insoluble powders and, moreover, these composites showed irregular "
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    ABSTRACT: Core-shell structured poly(3,4-ethylenedioxythiophene)/multi-walled carbon nanotubes (PEDOT/MWCNTs) nanofibers were synthesized through an interfacial polymerization technique. The interfacial polymerization at a liquid-liquid interface allowed PEDOT to grow uniformly on the surface of MWCNTs due to the presence of pi-pi interactions between PEDOT and MWCNTs walls. The morphology, structure and composition of the as-prepared PEDOT/MWCNTs were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy and Fourier transform infrared spectroscopy (FT-IR). In addition, the electrocatalytic properties of PEDOT/MWCNTs toward redox reactions of magnolol, a widely used traditional Chinese medicine, were systematically investigated. The results showed that the PEDOT/MWCNTs nanofibers exhibited a distinctly higher activity for the detection of magnolol compared with those of pure MWCNTs and PEDOT. The remarkably enhanced activity for the nanofibers can be attributed to the unique configuration and synergistic contribution between PEDOT and MWCNTs. The presented method is a general, facile and green approach for the synthesis of polymer/CNTs nanofibers, which is significant for the development of high performance electrocatalysts for biosensing and fuel cell applications.
    Electrochimica Acta 08/2014; 137:518-525. DOI:10.1016/j.electacta.2014.06.053 · 4.50 Impact Factor
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    • "It is also possible that Epon may have better thermal contacts with graphites and CNTs than Vinnapas. It has been found that the thermal conductivity can be dramatically improved by adding them into Epon [8] [38] rather than Vinnapas matrices [7] [20] [22] [23]. With the Epon thermal conductivity , k e was calculated to be 0.782 for sample 20 from Eq. (3) with a ¼ 4.97. "
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    ABSTRACT: Carbon nanotube- or/and graphite-filled polymer composites were synthesized by using simple mixing and drying methods, and their thermal conductivities and structures were characterized by using a steady-state method (ASTM D5470) and scanning and transmission electron microscopies. In order to investigate the influence of synthesis conditions on the thermal conductivity of composites, various concentrations of multiwall carbon nanotubes, graphites, surfactants, and polymer matrix materials as well as two different nanoparticles and solvents were tested. Our composites containing both nanotubes (25 wt. %) and graphites (25 wt. %) with sodium dodecyl benzene sulfonate (SDBS) as a dispersant showed the highest thermal conductivity, similar to 1.8 W/m-K at room temperature. The highest conductivity from nanotube/graphite mixtures would be from good adhesion and less voids between nanotubes and polymers as well as excellent thermal conduction from graphite sheets. The thermal conductivities of the composites have been calculated as a function of carbon nanotube concentrations by using a model based on the Max-well's effective medium theory, and the most effective method of improving thermal conductivity was suggested. [DOI: 10.1115/1.4005201]
    Journal of Heat Transfer 04/2012; 134(4):041302. DOI:10.1115/1.4005201 · 2.06 Impact Factor
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