Effect of Polyvinyl Alcohol on the Growth, Structure, Morphology, and Electrical Conductivity of Polypyrrole Nanoparticles Synthesized via Microemulsion Polymerization
Polypyrrole (PPy) nanoparticles were synthesized via microemulsion polymerization technique using sodium dodecyl sulfate as surfactant. Polyvinyl alcohol (PVA) was added as soft template during polymerization to modify the structure and properties of PPy nanoparticles. The synthesized materials namely, PVA-free and PVA added were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and DC electrical conductivity measurements. The sample synthesized in the presence of PVA has longer conjugation length as estimated from FT-IR investigation. Temperature dependence (4.2–300？K) of DC electrical conductivity measurement reveals that the PVA has a strong effect on the polymerization mechanism of PPy giving evidence of H-bonded assistance during polymerization leading to the synthesis of better ordered polymer. A growth mechanism has been proposed which explains the H-bonded assistance of PPy polymerization leading to enhanced structural ordering. 1. Introduction Conjugated polymers have attracted considerable attention in the past few decades because of their potential application in electronic devices [1]. Their ease of processing and chemically tunable properties makes them useful for electronic, optoelectronic, electromechanical, and sensing device application [2, 3]. During the recent years conducting polymer nanostructures have received increasing attention from both fundamental research as well as application point of view. Conducting polymer nanostructures show high electrical conductivity, large surface area, short path lengths for the transport of ions, and high electrochemical activity as compared to its macrogranular structure or self-supporting films [4–7]. It can be synthesized by several approaches such as well-controlled solution synthesis [8, 9], soft-template methods [10], hard-template methods [11], and electrospinning technology [12]. Recently some conducting polymer nanowires and nanorods have been synthesized via hydrogen bonding [13]. Polypyrrole (PPy) is one of the most studied conducting polymers because of its good environmental stability, facile synthesis, ion exchange capacity, biocompatibility, and higher conductivity [14, 15]. It can be used in drug delivery, rechargeable batteries, supercapacitors, anhydrous electrorheological fluids, microwave shielding, and corrosion protection [16–18]. Soft template uses microemulsion polymerization which allows particles to transfer into spherical aggregates through the surfactant template for the production of PPy
References
[1]
Z. Yao, H. W. C. Postma, L. Balents, and C. Dekker, “Carbon nanotube intramolecular junctions,” Nature, vol. 402, no. 6759, pp. 273–276, 1999.
[2]
K. Ramanathan, M. A. Bangar, M. H. Yun, W. Chen, A. Mulchandani, and N. V. Myung, “Individually addressable conducting polymer nanowires array,” Nano Letters, vol. 4, no. 7, pp. 1237–1239, 2004.
[3]
J. W. Gardner and P. N. Bartlett, “Brief history of electronic noses,” Sensors and Actuators B, vol. B18, no. 1, pp. 211–220, 1994.
[4]
J. Huang, S. Virji, B. H. Weiller, and R. B. Kaner, “Polyaniline nanofibers: facile synthesis and chemical sensors,” Journal of the American Chemical Society, vol. 125, no. 2, pp. 314–315, 2003.
[5]
H. Peng, L. Zhang, C. Soeller, and J. Travas-Sejdic, “Conducting polymers for electrochemical DNA sensing,” Biomaterials, vol. 30, no. 11, pp. 2132–2148, 2009.
[6]
R. J. Tseng, J. Huang, J. Ouyang, R. B. Kaner, and Y. Yang, “Polyaniline nanofiber/gold nanoparticle nonvolatile memory,” Nano Letters, vol. 5, no. 6, pp. 1077–1080, 2005.
[7]
N. R. Chiou, C. M. Lui, J. J. Guan, L. J. Lee, and A. J. Epstein, “Growth and alignment of polyaniline nanofibres with superhydrophobic, superhydrophilic and other properties,” Nature Nanotechnology, vol. 2, pp. 354–357, 2007.
[8]
D. Li and R. B. Kaner, “Shape and aggregation control of nanoparticles: not shaken, not stirred,” Journal of the American Chemical Society, vol. 128, no. 3, pp. 968–975, 2006.
[9]
N. R. Chiou and A. J. Epstein, “Polyaniline nanofibers prepared by dilute polymerization,” Advanced Materials, vol. 17, no. 13, pp. 1679–1683, 2005.
[10]
M. X. Wan, “A template-free method towards conducting polymer nanostructures,” Advanced Materials, vol. 20, no. 15, pp. 2926–2932, 2008.
[11]
M. Yang, J. Ma, C. L. Zhang, Z. Z. Yang, and Y. F. Lu, “General synthetic route toward functional hollow spheres with double-shelled structures,” Angewandte Chemie International Edition, vol. 44, no. 41, pp. 6727–6730, 2005.
[12]
M. K. Shin, Y. J. Kim, S. I. Kim et al., “Enhanced conductivity of aligned PANi/PEO/MWNT nanofibers by electrospinning,” Sensors and Actuators B, vol. 134, no. 1, pp. 122–126, 2008.
[13]
J. Zang, C. M. Li, S. J. Bao, X. Cui, Q. Bao, and C. Q. Sun, “Template-free electrochemical synthesis of superhydrophilic polypyrrole nanofiber network,” Macromolecules, vol. 41, no. 19, pp. 7053–7057, 2008.
[14]
Y. C. Liu and C. J. Tsai, “Enhancements in conductivity and thermal and conductive stabilities of electropolymerized polypyrrole with caprolactam-modified clay,” Chemistry of Materials, vol. 15, no. 1, pp. 320–326, 2003.
[15]
B. R. Saunders, R. S. Fleming, and K. S. Murray, “Recent advances in the physical and spectroscopic properties of polypyrrole films, particularly those containing transition-metal complexes as counteranions,” Chemistry of Materials, vol. 7, no. 6, pp. 1082–1094, 1995.
[16]
J. M. Pernaut and J. R. Reynolds, “Use of conducting electroactive polymers for drug delivery and sensing of bioactive molecules. A redox chemistry approach,” The Journal of Physical Chemistry B, vol. 104, no. 17, pp. 4080–4090, 2000.
[17]
K. Jurewicz, S. Delpeux, V. Bertagna, F. Béguin, and E. Frackowiak, “Supercapacitors from nanotubes/polypyrrole composites,” Chemical Physics Letters, vol. 347, no. 1–3, pp. 36–40, 2001.
[18]
J. W. Goodwin, G. M. Markham, and B. Vinent, “Studies on model electrorheological fluids,” The Journal of Physical Chemistry B, vol. 101, no. 11, pp. 1961–1967, 1997.
[19]
J. Jang and J. H. Oh, “Novel crystalline supramolecular assemblies of amorphous polypyrrole nanoparticles through surfactant templating,” Chemical Communications, no. 19, pp. 2200–2201, 2002.
[20]
Y. Liu and Y. Chu, “Surfactant-assisted synthesis of single crystal BaWO4 octahedral microparticles,” Materials Chemistry and Physics, vol. 92, no. 1, pp. 59–63, 2005.
[21]
F. Yan, G. Xue, and M. Zhou, “Preparation of electrically conducting polypyrrole in oil/water microemulsion,” Journal of Applied Polymer Science, vol. 77, no. 1, pp. 135–140, 2000.
[22]
M. K. Song, Y. T. Kim, B. S. Kim, J. Kim, K. Char, and H. W. Rhee, “Synthesis and characterization of soluble polypyrrole doped with alkylbenzenesulfonic acids,” Synthetic Metals, vol. 141, no. 3, pp. 315–319, 2004.
[23]
Y. Liu, Y. Chu, and L. Yang, “Adjusting the inner-structure of polypyrrole nanoparticles through microemulsion polymerization,” Materials Chemistry and Physics, vol. 98, no. 2-3, pp. 304–308, 2006.
[24]
M. Omastová, M. Trchová, J. Kovarová, and J. Stejskal, “Synthesis and structural study of polypyrroles prepared in the presence of surfactants,” Synthetic Metals, vol. 138, no. 3, pp. 447–455, 2003.
[25]
V. P. Menon, J. Lei, and C. R. Martin, “Investigation of molecular and supermolecular structure in template-synthesized polypyrrole tubules and fibrils,” Chemistry of Materials, vol. 8, no. 9, pp. 2382–2390, 1996.
[26]
R. K. Singh, A. Kumar, K. Agarwal et al., “DC electrical conduction and morphological behavior of counter anion-governed genesis of electrochemically synthesized polypyrrole films,” Journal of Polymer Science Part B, vol. 50, no. 5, pp. 347–360, 2012.
[27]
N. F. Mott and E. A. Davis, Electronic Processes in Noncrystalline Materials, Oxford University Press, London, UK, 2nd edition, 1979.
[28]
R. K. Singh, A. Kumar, and R. Singh, “Mechanism of charge transport in poly(2,5-dimethoxyaniline),” Journal of Applied Physics, vol. 107, no. 11, Article ID 113711, 7 pages, 2010.
[29]
Z. H. Wang, A. Ray, A. G. MacDiarmid, and A. J. Epstein, “Electron localization and charge transport in poly(o-toluidine): a model polyaniline derivative,” Physical Review B, vol. 43, no. 5, pp. 4373–4384, 1991.
[30]
D. S. Maddison and T. L. Tansley, “Variable range hopping in polypyrrole films of a range of conductivities and preparation methods,” Journal of Applied Physics, vol. 72, no. 10, pp. 4677–4682, 1992.
