https://doi.org/10.1351/goldbook.08785
A polymer composed of molecules whose backbone is a sequence of alternating single and multiple bonds:
where \(\ce{R^{1}}\) and \(\ce{R^{2}}\) are each hydrogen, alkyl, aryl or heteroaryl and Ar is arenediyl (formerly: arylene) or heteroarenediyl (formerly: heteroarylene).
Notes:
- Overlaps of neighboring \(\ce{\uppi {-}orbitals}\) across intervening \(\ce{\upsigma {-}bonds}\) in a conjugated molecule results in delocalization of π-electrons along the molecule backbone. This effect which, however, is limited by Peierls distortion gives the electric conductivity to conjugated polymers.
- Conjugated polymers are mostly linear or branched polymers. However, they can also have a dendritic, hyperbranched, network, rotaxane or metallo-supramolecular chain architecture.
- Polymers such as polysilanes, polygermanes and polystannanes with significantly occupied LUMO orbitals due to low bandgap energy and thus show the delocalization of electrons sometimes called \(\ce{\upsigma {-}conjugated polymers}\).
Source:
PAC, 2022, 94, 15. 'Glossary of terms relating to electronic, photonic and magnetic properties of polymers (IUPAC Recommendations 2021)' on page 20 (https://doi.org/10.1515/pac-2020-0501)
PAC, 2022, 94, 15. 'Glossary of terms relating to electronic, photonic and magnetic properties of polymers (IUPAC Recommendations 2021)' on page 20 (https://doi.org/10.1515/pac-2020-0501)