The Ziegler-Natta polymerization of 3-ethynylphenanthrene resulted in cis-cisoidal (red and insoluble) and cis-transoidal (red-brown and soluble) poly(3-ethynylphenanthrene) structures. Trans-cisoidal (brown and soluble) poly(3-ethynylphenanthrene) has been obtained using phosphine complexes or by a thermal initiation method. The cis-cisoidal and cis-transoidal structures thermally isomerize in the solid state (at about 240° and 220° respectively), leading to a soluble trans-cisoidal compound. © 1978.
Simionescu, C. I., Dumitrescu, S., & Grigoras, M. (1978). On the polymerization of acetylenic derivatives-XXIX. Synthesis and properties of poly(3-ethynylphenanthrene) isomers. European Polymer Journal, 14(12), 1051–1057. https://doi.org/10.1016/0014-3057(78)90166-0