Synthesis and characterization of conducting polymer nanostructures and their application in sensors
"A one-step synthesis technique has been used to fabricate sensors by growing polyaniline nanofibers and polyaniline/metal nanocomposites in the active area of an interdigitated electrode array. Polyaniline nanofiber sensors can be fabricated by irradiating an aqueous precursor solution containing aniline, HCl, a metal salt, and ammonium persulfate (APS) with a high pressure Hg lamp. The sensors are ready for operation after polymerization is complete, and no additional processing steps are necessary. These sensors showed faster and more intensity response to various organic vapors than conventional bulk polyaniline sensors due to their larger surface area. A chemisorption model and a diffusion model were used to fit the sensor response of nanostructured polyaniline sensors. Both models can mathematically fit the sensor response as a function of time. Fitting errors from the two models were in a reasonable range, both allowing reasonable mathematical forms for the time-dependent and concentration behavior. An oligomer-assisted polymerization method was carried out to synthesize polythiophene nanofibers. In this approach, a solution of thiophene, FeCl₃, and terthiophene was dissolved in acetonitrile. Compared to conventional chemical polymerization, a polythiophene oligomer, terthiophene or bithiophene, was added to assist the formation of nanofibers. The polythiophene collected after the 12 h reaction time was found to have nanofibrilar morphology with an average diameter of about 40-50 nm. Unlike other hard-template or soft-template techniques, this method does not require the introduction of a heterogeneous phase"--Abstract, page iv.
Missouri University of Science and Technology
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