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Morphology characterization of polyaniline nano- and microstructures

Hopkins, Alan R. and Lipeles, Russell A. and Hwang, Son-Jong (2008) Morphology characterization of polyaniline nano- and microstructures. Synthetic Metals, 158 (14). pp. 594-601. ISSN 0379-6779. doi:10.1016/j.synthmet.2008.04.018.

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Small-angle neutron scattering (SANS), nuclear magnetic resonance (NMR), wide-angle and small-angle X-ray scattering (WAXS and SAXS) measurements were carried out to investigate the three morphological forms of polyaniline emeraldine base (PANI-EB): unstructured, microtubes, and nanofibers. Although the chemical backbone between these two materials is quite similar, their solid structures are quite different, showing differences in the molecular conformation and supramolecular packing. Detailed solid-state 13C and 15N NMR characterization of PANI nanofibers (compared to the unstructured, granular form) revealed a slight variation in the structural features of the polymer that led to some differences in the chemical environments of the respective nuclei. The presence of two extra-sharp peaks at 96.5 and 179.8 ppm is a distinct feature found exclusively in the nanofiber spectra. Moreover, the crosspolarization (CP) dynamics study disclosed the presence of a complete set of sharp NMR peaks that are responsible for the presence of a more ordered morphology in the nanofiber. Small-angle neutron scattering indicated very sharp interfaces in the PANI fibers, which are well organized and have extremely sharp domains within the length scales probed (not, vert, similar10–1 nm). Overall, the X-ray scattering and spectroscopy data suggest that the nanofiber form is structurally different from the unstructured, PANI-EB powder. These differences are manifested, in part, by the additional chemistry occurring during the synthesis of the nanofibers.

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Hwang, Son-Jong0000-0002-3210-466X
Additional Information:© 2008 Elsevier. Received 15 October 2007; revised 12 March 2008; accepted 15 April 2008. Available online 16 June 2008. This work was supported under The Aerospace Corporation's Independent Research and Development (IRAD) program. The authors would like to specially thank Professor Matthew P. Espe of the University of Akron for helpful insight and discussion on NMR analyses. Also, we would like to thank Dr. Li-Piin Sung of the National Institute of Standards and Technology (NIST) for allowing use of their SANS instrument and interpretation of the data. The Caltech NMR facility was supported by the National Science Foundation (NSF) under Grant Number 9724240 and partially supported by the MRSEC Program of the NSF under Award Number DMR-0520565. Finally we would like to thank Dr. Wei H. Kao (The Aerospace Corporation) for many helpful discussions and support for investigating these nanomaterials.
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Aerospace CorporationUNSPECIFIED
Subject Keywords:Polyaniline emeraldine base (PANI-EB); Nanofibers; Microtubes; Solid-state nuclear magnetic resonance; Wide-angle X-ray scattering; Small-angle X-ray scattering
Issue or Number:14
Record Number:CaltechAUTHORS:HOPsm08
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:11841
Deposited By: Archive Administrator
Deposited On:06 Oct 2008 03:53
Last Modified:08 Nov 2021 22:22

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