A novel hydrophilic pyridinium salt polymer/SWCNTs composite film for high thermoelectric performance

Polymer/carbon nanotube composites have gained great progress in the past decade. However, the lack of scalability of production due to the relatively high volatility and strong toxicity of the dispersion solvent have created a great need for environmental friendly process for expanding TE applications. In this work, organic-inorganic composite films composed of a novel hydrophilic pyridinium salt polymer (noted as P2) and SWCNTs were prepared for thermoelectric application. The novel hydrophilic pyridinium salt polymer was designed and synthesized containing the pyridinium salt for aqueous dissolution and thiophenes as the conjugation group to make the polymer/CNT composite film electrical connecting, therefore improving the thermoelectric performance. Another pyridinium salt polymer (noted as P1) without thiophene group was also synthesized for the purpose of comparison. The polymers attach on the surface of CNTs through pi-pi conjugation interaction between conjugation groups and pi-electrons of CNTs. The P2/CNT composites were homogeneously dispersed in the aqueous solution, revealing better dispersion behavior than P1/CNT, which is probably because of the stronger contact interaction between P2/CNT than P1/CNT due to the higher electron delocalization of polymer P2 than P1. The electrical conductivity of P2/CNT composite film reached the maximum value of 159 S/cm with 50% CNT content. Consequently, a high power factor of 46.4 mu W/mK(2) was obtained for the P2/50% CNT composite film. (C) 2017 Published by Elsevier Ltd.