Anisotropic ionic conductivity of lithium-doped sulfonated PBI

• Published in: Journal of polymer science. Part B, Polymer physics Vol. 35; no. 17; pp. 2925 - 2933
• Main Authors: Spry, R. J., Alexander Jr, M. D., Bai, S. J., Dang, T. D., Price, G. E., Dean, D. R., Kumar, B., Solomon, J. S., Arnold, F. E.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: New York John Wiley & Sons, Inc 01.12.1997; Wiley
• Subjects: anisotropic; Applied sciences; conducting polymers; DC conductivity; depletion measurement; Electrical, magnetic and optical properties; Exact sciences and technology; ionic conductivity; Organic polymers; Physicochemistry of polymers; polyelectrolyte; polymer electrolyte; Properties and characterization; rigid-rod polymer; X-ray scattering; Electrical properties; Voltage current curve; Ionic conductivity; Aromatic polymer; Polymer solid electrolyte; Benzimidazole derivative polymer; Experimental study; Polyelectrolyte; Conjugated polymer; Sulfonate polymer; Anisotropy; Supramolecular structure; Lithium compound; Rigid chain
• ISSN: 0887-6266; 1099-0488
• DOI: 10.1002/(SICI)1099-0488(199712)35:17<2925::AID-POLB15>3.0.CO;2-9

The conductivity study results of lithium‐doped sulfonated PBI, a conjugated rigid rod polymer, poly[(1,7‐dihydrobenzo[1,2‐d:4,5‐d′]dimidazole‐2,6‐diyl)‐2‐(2‐sulfo)‐p‐phenylene], derivatized with pendants of propane sulfonate Li+ ionomer are reported. The room‐temperature DC four‐probe conductivity parallel to the surface of cast films was as large as 8.3 × 10−3 S/cm. Similar measurements with an eight‐probe configuration showed no difference between bulk and surface conductivity. The ionic nature of the conductivity was indicated by constant voltage depletion experiments and by secondary ion mass spectroscopy measurements of the residues near the electrodes. The DC two‐probe conductivity measured transverse to the sample surface was three to four orders of magnitude smaller than longitudinal conductivity, while the AC two‐probe conductivity was even less. Electron microscopy indicated that the films had a layered structure parallel to the surfaces. This structural anisotropy was confirmed by refractive index values obtained from wave‐guide experiments and by wide angle X‐ray scattering. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 2925–2933, 1997