Development of polypyrrole-coated cotton thermoelectric fabrics

Polypyrrole (PPy) is most widely used conductive polymer for conductive textile applications owing to its excellent electrical conductivity, good electromagnetic shielding, good anti-bacterial properties, etc. However, it has not been explored much as thermoelectric material. PPy can be coated on cotton fabric in aqueous media from its monomer to prepare electro-conductive fabrics, which will be a flexible organic thermoelectric material. In this study, PPy-coated cotton fabrics are prepared by in situ chemical polymerisations of pyrrole in presence of ferric chloride. The polymerisation process is optimised by employing Box-Behnken response surface design and method of steepest ascent to achieve minimum electrical resistivity. The lowest resistivity of PPy-coated cotton fabric is achieved to be 1.23 omega/cm after the optimisation. The PPy-coated cotton fabric with copper thermocouple shows Seebeck coefficient as high as 11.95 mu V/K, power factor 0.139 mu W m(-1) K-2, and thermoelectric figure of merit 1.22 x 10(-4) at an absolute temperature of 300K. The thermoelectric performance of this coated fabric is found to be comparable to other costly conductive polymers and inorganic semiconductors. The surface morphology of PPy-coated cotton fabric is observed by field-emission scanning electron microscopy. Chemical interaction between cotton and PPy is investigated by FTIR spectroscopy. Analysis of semi-crystalline structure is done by X-ray diffraction and thermo-gravimetric analyser is used for analysis of thermal degradation.