Conduction Mechanisms in Polyaniline (Review)

Introduction. Polyaniline (PANI) demonstrates a unique combination of electrophysical properties, stability, and ease of synthesis, making this material one of the most promising conductive polymers. Its ability to significantly alter electrical conductivity during protonation provides broad opportunities for tailoring the functional characteristics of materials. Despite extensive research, the charge transfer mechanisms in PANI-based systems remain insufficiently studied. The lack of a unified theoretical model describing the relationship between chemical structure and electronic properties poses significant limitations for the targeted development of PANI-based materials with specified parameters.

Aim. To generalize current knowledge of conduction mechanisms in PANI and to develop a comprehensive approach integrating polaron theory and hopping conductivity models.

Materials and methods. The selection of literature sources for review was conducted using a chronological approach covering a period of over 10 years, driven by the need for a retrospective analysis of the evolution of modern views on conduction mechanisms in PANI and the extension of its application areas. The criterion for forming the final set of sources was the presence of factual data relevant to the research topic.

Results. The analysis revealed the predominance of the polaron conduction mechanism in protonated PANI and highlighted the inadequacy of existing theoretical models (such as variable-range hopping and tunneling mechanisms) in providing a comprehensive description of its electronic properties. This necessitates the development of a comprehensive approach integrating elements of various transport theories.

Conclusion. The analysis of modern theoretical approaches to describing conductivity in PANI revealed fundamental differences between hopping transport and tunneling mechanism models. It is noted that none of the concepts possesses sufficient predictive power regarding the spatial distribution of charge transfer. The obtained results indicate the need to develop a synthetic theory combining the methodological advantages of the considered approaches. The creation of such a hybrid model will facilitate progress in the design of PANI-containing materials with tailored electrophysical characteristics.

1. McNeill R., Siudak R., Wardlaw Jh., Weiss D. E. Electronic Conduction in Polymers. I. The Chemical Structure of Polypyrrole. Australian J. of Chemistry. 1963, vol. 16, no. 6, pp. 1056–1075. doi: 10.1071/CH9631056

2. Boeva Z. A., Sergeyev V. G. Polyaniline: Synthesis, Properties, and Application. Polymer Science Series C. 2014, vol. 56, no. 1, pp. 144–153. doi: 10.1134/S1811238214010032

3. Yang P., Sun P., Chai Zh., Huang L., Cai X., Tan Sh., Song J., Mai W. Large‐Scale Fabrication of Pseudocapacitive Glass Windows That Combine Electrochromism and Energy Storage. Angewandte Chemie. 2014, vol. 126, no. 44, pp. 12129–12133. doi: 10.1002/ange.201407365

4. Almtiri M., Dowell T., Giri H., Wipf D. O., Scott C. N. Electrochemically Stable Carbazole-Derived Polyaniline for Pseudocapacitors. ACS Applied Polymer Materials. 2022, vol. 4, no. 5, pp. 3088–3097. doi: 10.1021/acsapm.1c01616

5. Mozafari M., Chauhan N. P. S. Fundamentals and Emerging Applications of Polyaniline. Netherlands, Elsevier, 2019, 308 p.

6. News of Nanotechnology. Nano- and Microsystem Engineering. 2005, no. 7, pp. 45–51. (In Russ.)

7. Shirsat M. D., Bangar M. A., Deshusses M. A., Myung N. V., Mulchandani A. Polyaniline NanowiresGold Nanoparticles Hybrid Network Based Chemiresistive Hydrogen Sulfide Sensor. Applied Physics Let. 2009, vol. 94, no. 8, art. no. 083502. doi: 10.1063/1.3070237

8. Zhai D., Liu B., Shi Yi, Pan L., Wang Ya., Li W., Zhang R., Yu G. Highly Sensitive Glucose Sensor Based on Pt Nanoparticle/Polyaniline Hydrogel Heterostructures. ACS Nano. 2013, vol. 7, no. 4, pp. 3540–3546. doi: 10.1021/nn400482d

9. Zhao L., Wang W., Wang A., Yuan K., Chen Shi, Yang Yu. A Novel Polyquinone Cathode Material for Rechargeable Lithium Batteries. J. of Power Sources. 2013, vol. 233, pp. 23–27. doi: 10.1016/j.jpowsour.2013.01.103

10. Zhang K., Zhang L. L., Zhao X. S., Wu J. Graphene/Polyaniline Nanofiber Composites as Supercapacitor Electrodes. Chemistry of Materials. 2010, vol. 22, no. 4, pp. 1392–1401. doi: 10.1021/cm902876u

11. Lachinov A. N., Salikhov R. B., Bunakov A. A. Charge Transport Mechanisms in Thin Polymer Films. Izvestia: Herzen University J. of Humanities & Sciences. 2015, vol. 5, no. 13, pp. 80–91. (In Russ.)

12. Bhandari S. Polyaniline: Structure and Properties Relationship. Polyaniline Blends, Composites and Nano-composites. 2018, pp. 23–60. doi: 10.1016/B978-0-12-809551-5.00002-3

13. Stejskal J., Kratochvíl P., Jenkins A. D. The Formation of Polyaniline and the Nature of Its Structures. Polymer. 1996, vol. 37, no. 2, pp. 367–369. doi: 10.1016/0032-3861(96)81113-X

14. Chiang J. C., MacDiarmid A. G. ‘Polyaniline’: Protonic Acid Doping of the Emeraldine Form to the Metallic Regime. Synthetic Metals. 1986, vol. 13, no. 1–3, pp. 193–205. doi: 10.1016/0379-6779(86)90070-6

15. Stafström S., Brédas J. L., Epstein A. J., Woo H. S., Tanner D. B., Huang W. S., MacDiarmid A. G. Polaron Lattice in Highly Conducting Polyaniline: Theoretical and Optical Studies. Physical Review Let. 1987, vol. 59, no. 13, pp. 1464–1467. doi: 10.1103/PhysRevLett.59.1464

16. MacDiarmid A. G., Chiang J. C., Richter A. F., Epstein A. J. Polyaniline: a New Concept in Conducting Polymers. Synthetic Metals. 1987, vol. 18, no. 1–3, pp. 285–290. doi: 10.1016/0379-6779(87)90893-9

17. Timonov A. M., Vasilyeva S. V. Electron Conductivity of Polymeric Compounds. Soros Educational J. 2000, vol. 6, no. 3, pp. 33–39. (In Russ.)

18. Inzelt G., Pineri M., Schultze J. W., Vorotyntsev M. A. Electron and Proton Conducting Polymers: Recent Developments and Prospects. Electrochimica Acta. 2000, vol. 45, no. 15–16, pp. 2403–2421. doi: 10.1016/S0013-4686(00)00329-7

19. Jaiswal M., Menon R. Polymer Electronic Materials: A Review of Charge Transport. Polymer International. 2006, vol. 55, no. 12, pp. 1371–1384. doi: 10.1002/PI.2111

20. Roth S., D. Carroll D. One-Dimensional Metals. 3rd ed. Weinheim, Wiley-VCH, 2014, 335 p.

21. Huang D., Xie D., Gao J., Lv W., Hong Sh. Pressure Dependence of the Electrical Resistivity in Polymer Polyaniline. Advances in Materials Science and Engineering. 2013, vol. 2013, no. 1, art. no. 124365. doi: 10.1155/2013/124365

22. Kwon O., McKee M. L. Calculations of Band Gaps in Polyaniline from Theoretical Studies of Oligomers. The J. of Physical Chemistry B. 2000, vol. 104, no. 8, pp. 1686–1694. doi: 10.1021/jp9910946

23. McCall R. P., Ginder J. M., Leng J. M., Ye H. J., Manohar S. K., Masters J. G., Asturias G. E., MacDiarmid A. G., Epstein A. J. Spectroscopy and Defect States in Polyaniline. Physical Review B. 1990, vol. 41, no. 8, art. no. 5202. doi: 10.1103/PhysRevB.41.5202

24. Liu W., Kumar Ja., Tripathy S., Senecal K. J., Samuelson L. Enzymatically Synthesized Conducting Polyaniline. J. of the American Chemical Society. 1999, vol. 121, no. 1, pp. 71–78. doi: 10.1021/ja982270b

25. Wu C. G., Bein T. Polyaniline Wires in Oxidant-Containing Mesoporous Channel Hosts. Chemistry of Materials. 1994, vol. 6, no. 8, pp. 1109–1112. doi: 10.1021/cm00044a008

26. Gueye M. N., Carella A., Faure-Vincent J., Demadrille R., Simonato J.-P. Progress in Understanding Structure and Transport Properties of PEDOTBased Materials: A Critical Review. Progress in Materials Science. 2020, vol. 108, art. no. 100616. doi: 10.1016/j.pmatsci.2019.100616

27. Rudenko R. M., Voitsihovska O. O., Poroshin V. N. Sequential change of semiconductor mechanisms of electrical conductivity in ternary PVDF/polyaniline/MWCNT nanocomposite in the wide temperature range of 4.2– 340 K. Materials Let. 2023, vol. 350, art. no. 134976. doi: 10.1016/j.matlet.2023.134976

28. Zhmurova A. V. Mechanisms of Electrical Conductivity in Nanocomposites with a Conductive Polymer Matrix. Science and Modernity. 2015, no. 39, pp. 103–108. (In Russ.) doi: 10.1002/app.44703

29. Bhandari S., Khastgir D. Synergistic Effect of Simultaneous Dual Doping in Solvent-Free Mechanochemical Synthesis of Polyaniline Supercapacitor Comparable to the Composites With Multiwalled Carbon Nanotube. Polymer. 2015, vol. 81, pp. 62–69. doi: 10.1016/j.polymer.2015.10.015

30. Mott N. F., Davis E. A. Electronic Processes in Non-Crystalline Materials. Oxford, Oxford University Press, 2012, 608 p. doi: 10.1080/00107514.2014.933254

31. Fosong W., Jinsong T., Lixiang W., Hongfang Zh., Zhishen Mo. Study on the Crystallinity of Polyaniline. Molecular Crystals and Liquid Crystals. 1988, vol. 160, no. 1, pp. 175–184. doi: 10.1080/15421408808083012

32. Éfros A. L., Shklovskii B. I. Coulomb Gap and Low Temperature Conductivity of Disordered Systems. J. of Physics C: Solid State Physics. 1975, vol. 8, no. 4, p. L49. doi: 10.1088/0022-3719/8/4/003

33. Wang Z. H., Scherr E. M., MacDiarmid A. G., Epstein A. J. Transport and EPR Studies of Polyaniline: a Quasi-One-Dimensional Conductor with Three-Dimensional "Metallic" States. Physical Review B. 1992, vol. 45, no. 8, art. no. 4190. doi: 10.1103/PhysRevB.45.4190