Novel strategies for the deposition of -COOH functionalized conducting copolymer films and the assembly of inorganic nanoparticles on conducting polymer platforms
Additional Document Info
A method for the preparation of -COOH functionalized conducting copolymer films; toward the ultimate goal of developing resistance-based sensing platforms, is presented. The method involved vapor phase copolymerization of pyrrole with a monomer containing the -COOH functionality, thiophene-3-acetic acid (TAA). This copolymerization strategy aided in avoiding the need to employ brittle poly(thiophene-3-acetic acid) (PTAA) films in sensing applications. In this strategy, variation in the gas phase feed ratio of pyrrole to TAA allowed for the variation of the composition of the copolymer film and further allowed for the variation of both the conductivity and the amount of -COOH functionality in the films. Further, the effect of covalent attachment of silver on the conductivity of the copolymer films is performed and presented. This covalent attachment of silver served the dual purpose of verifying the presence of active -COOH groups on the surface, and also allowed for the quantification of the change in conductivity as a result of such attachment. Use of the conjugated ring containing 4-aminothiophenol as the linker material enhanced the conductivities of the films. In contrast, employing cysteamine to link silver nanoparticles to the copolymer films did not result in any enhancement in the conductivities. An enhancement in the conductivities, ranging from 2 to 1000 times, is observed on covalent attachment of silver nanoparticles to the copolymer films using 4-aminothiophenol as the linker material. This increase depended on the amount of TAA in the films and increased with increasing concentrations of TAA in the films. These results clearly indicate the use of these copolymer films in resistance-based sensing. Further, this covalent attachment could be used as a novel strategy to integrate other inorganic nanomaterials on conducting polymer platforms. 2008 WILEY-VCH Verlag GmbH & Co. KGaA.