Chemical detection polyaniline nanofibers

This book has been divided into three areas chemical detection, biological detection, and decontamination. The subject matter in the chapters include cross-linked divinyl benzene-substituted methacrylate polymers (Chapter 2), porous silicon (Chapter 3), reactive glass surfaces (Chapter 4), polycarbosilanes (Chapter 5), non-aqueous, chemically cross-linked polybutadiene gels (Chapter 6), conducting polyaniline nanofibers (Chapter 7), organically doped polystyrene and polyvinyltoluene (Chapter 8), electroplated polymer cast resins (Chapter 9), self assembled monolayers (Chapter 10), amphiphilic functionalized norbomene polymers (Chapter 11), transition metal substituted polyoxometalates (POMs) (Chapter 12), cross-linked divinyl-benzamide phospholipids (Chapter 13), and silica and organo silyl polymers (Chapter 14). 

Detection of Toxic Chemicals for Homeland Security Using Polyaniline Nanofibers, Chapter 7... 

To further examine these materials, analyte concentrations will be varied to determine the ranges of response and the limits of detection. Other work in progress is geared toward the measurement of nanofiber responses with varying humidity and temperature environments. In addition, diffusion studies are planned in order to more fully understand the interaction of analytes with the nanofibers. We are also working on developing new composite materials with polyaniline nanofibers in order to control the response of conducting polymers to chemicals of interest for these and other new applications. 

Conventional polyaniline has been previously used as a chemical sensor but has been limited in its sensitivity and time response. Previous work on enhancing the detection capabilities of polyaniline has included the use of thinner films (6). The disadvantages of this method are the loss of robustness of the film and the difficulty in making such thin films with good control. Another way to increase sensitivity to gases is to change the morphology of the polyaniline. In particular, nanostructured forms of polyaniline, such as nanowires, nanofibers, or nanorods, have recently received much attention because their small diameters are expected to allow for fast diffusion of gas molecules into the structures (7). 

FIGURE 13.6 Response of a nanofiber film (solid line) and a conventional film (dotted Une) upon exposure to 100 ppm NH3 vapor (left) and 100 ppm HCl vapor (right). Doped and dedoped polyaniline were used to detect NH3 and HCl, respectively. R/Ro is the resistance (R) normalized to the initial resistance (/fo) prior to gas exposure. Reprinted with permission from [82]. Copyright 2008 American Chemical Society. 

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