(643c) Carboxylic Acid Functionalized Conducting Polymer Films for Sensing Applications

Uniform, highly conductive, coatings of carboxylic acid functionalized conducting polymer films were obtained using the oxidative chemical vapor deposition (oCVD) process. These films were obtained by copolymerization ethylenedioxythiophene (EDOT), with a monomer having the carboxylic acid functionality. Monomer with carboxylic acid functionality, thiophene-3-carboxylic acid, was employed for this purpose. Iron chloride (FeCl₃) is used as the oxidizing agent for the oCVD process. The addition of EDOT to thiophene-3-carboxylic acid not only allowed for the supply of the solid phase thiophene-3-carboxylic acid through the vapor phase, but also in obtaining highly conductive copolymer films, with ?COOH functional groups on the surface. The presence of carboxylic acid functional group in the obtained films was confirmed using FTIR and XPS analysis. Four-point probe measurements showed that the EDOT-co-thiophene-3-carboxylic acid copolymer films are highly conductive and have conductivities as high as 200 S/cm. Absorption spectroscopy on the samples showed that the inclusion of thiophene-3-carboxylic acid shifts the absorption peak of PEDOT by about 80 nm, further confirming the presence of thiophene-3-carboxylic acid in the films. In addition, coatings obtained on spun-coated polyacrylonitrile fiber membranes were found to be highly conformal. These high surface area, highly conductive -COOH functionalized films are very useful in the development of resistance-based biosensing platforms.