https://doi.org/10.1351/goldbook.08785
A polymer composed of molecules whose backbone is a sequence of alternating single and multiple bonds:
where and are each hydrogen, alkyl, aryl or heteroaryl and Ar is arenediyl (formerly: arylene) or heteroarenediyl (formerly: heteroarylene).

Notes:
- Overlaps of neighboring
across intervening 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
.