Preparation and characterization of aqueous dispersions of poly(3,4‐ethylenedithiathiophene‐co‐3,4‐ethylenedioxythiophene)/ poly(styrene sulfonate) and their conducting films

The chemical oxidative copolymerization of 3,4‐ethylenedithiathiophene (EDTT) with 3,4‐ethylenedioxythiophene (EDOT) and 2′‐hydroxymethyl‐3,4‐ethylenedioxythiophene in a poly(styrene sulfonic acid) aqueous solution was successfully carried out to form stable, dark blue colloidal dispersions in water. Coating these dispersions onto polypropylene substrates led to the formation of free‐standing copolymer films. The mechanical, electrical, and thermoelectrical properties of these films were investigated; the films showed superior properties in comparison with those of poly(3,4‐ethylenedithiathiophene) (PEDTT)/poly(styrene sulfonate) (PSS). The copolymer film based on EDTT and EDOT achieved a high electrical conductivity (8.2 × 10^?2 S cm^?1) at 298 K; this could be improved about 10 times through the addition of dimethyl sulfoxide (DMSO) or DMSO/isopropyl alcohol into the polymer dispersion with almost constant Seebeck coefficients of about 9 μV K^?1. On the contrary, these additives had almost no effect on the conductivity of PEDTT/PSS. The structure and morphology of the polymer films were studied by X‐ray diffraction and SEM analyses. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013