A theoretical investigation of chain packing and electronic band structure of the rigid-rod polymer trans-poly(p-phenylene benzobisthiazole) in the crystalline state
✍ Scribed by Bhaumik, D. ;Mark, J. E.
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 1983
- Tongue
- English
- Weight
- 336 KB
- Volume
- 21
- Category
- Article
- ISSN
- 0098-1273
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✦ Synopsis
Abstract
The extended Hückel method was employed to calculate electronic band structures in trans‐poly(p‐phenylene benzobisthiazole) (trans‐PBT) in an attempt to elucidate the packing and electronic properties of these chains in the crystalline state. The unit‐cell energies thus calculated indicate that the most stable arrangement for trans‐PBT corresponds to the chains in planar configurations, at an interplanar spacing of 3.5 Å, and shifted axially by 3.0 Å relative to one another. These calculated results are in good agreement with experimental results obtained on the polymer and on relevant model compounds. No discernible dispersion of the energy bands perpendicular to the planes is observed, indicating that the neighboring chains are electronically noninteractive, as was found earlier for trans‐polyacetylene and polyethylene. Similarly, the band gap of 1.69 eV in the axial direction for one of a pair of chains was nearly the same as that, 1.73 eV, calculated previously for an isolated trans‐PBT chain. These values are in the range 1.4–1.9 eV reported for trans‐polyacetylene, which has been extensively studied because of its promise as a semiconductor.