Polytriacetylene backbones

J.2 Stable Soluble Conjugated Carbon Rods with a Polytriacetylene Backbone... 

Scheme 13-14 Preparation of the soluble carbon rods 58a-e which have a polytriacetylene backbone. The length shown is the distance between the two extreme tips of the end-capping phenyl rings.

Anthony, J.A., Boudon, C., Diederich, E, Gisselbrecht, J.R, GramHch, V, Gross, M., Hobi, M., and Seiler, R, Stable, soluble, conjugated carbon rods with a persilylethynylated polytriacetylene backbone, Angew. Chem. Int. Ed. Engl, 33, 763,1994. 

Fig. 15. Examples of conjugated polymers. The dotted lines indicate bonds lateral to the conjugated backbone. R and R2 denote end groups. The simplest conjugated polymer is polyene with alternating single and double bonds. By introducing triple bonds, one goes from polyene over polydiacetylene and polytriacetylene to polycarbyne. The aromatic polyphenylene and polyphenylenevinylene contain additional phenyl rings. Polythiophenes additionally possess sulfur atoms...

In polytriacetylenes (Fig. 19) the conjugation across the backbone is weaker than for polyenes. Conversely, the PTAs are stable under normal laboratory condition and show no degradation over months, which makes them an interesting candidate for applications. Furthermore, the chemical synthesis allows to have a well defined number of monomer units and to attach definite functional groups enabling the study of the structure-property relationships in nonlinear optics. 

The pure TMS and TES polytriacetylene oligomer series were investigated including a polymer sample. The different end groups in the polymer have a negligible influence on the molecular property as the PTA backbone is long enough to dominate the molecular properties. 

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