(548b) Volatile Organic Compound Sensor Based on Conducting Polymer-Metal Nanoparticle Composites

Chemically selective, cheap and robust chemresistor platforms, based on novel metal nanoparticle-conducting polymer composites, for sensing volatile organic compounds were developed and presented. These composites were obtained by covalent attachment and assembly of metal nanoparticles on top of functionalized conducting polymer platforms. This integration strategy allowed for the uniform assembly of metal nanoparticles on top of the conducting polymer films, while preserving the active metal surface. The fabrication of these composites involved the following steps: (i) Use of oxidative Chemical Vapor Deposition (oCVD) for obtaining uniform films of poly(3,4-ethylenedioxythiophene-co-thiophene-3-acetic acid), P(EDOT-co-TAA), and (ii) covalently tethering metal nanoparticles on top of these conducting polymer films using conjugated linker molecules, such as 4-aminothiophenol.

Metal nanoparticle layers on top of these platforms served as the sensing elements in these platforms. Nobel metals exhibit a change in work function on exposure to gases and vapors. The magnitude of this change depends on the gas (or vapor) it is exposed to and its concentration. By assembling metal nanoparticles on top of conducting polymers, these changes in work function could be translated into changes in resistance of the composites and detected easily. Selectivity in sensing volatile organic compounds was accomplished by varying the material of the metal assembled on top of the P(EDOT-co-TAA) films. Selective sensing of acetone and toluene was accomplished by assembling palladium and nickel on top of the conducting polymer films, respectively. Concentrations of acetone and toluene as low as 171 ppm and 51 ppm, respectively, were detected using these platforms. The response of these composites to these volatile organic compounds was found to be instantaneous (few seconds), and recovery was also observed to be fast (20-40 seconds).